## Interactive session for prepared example 12

```
*******************************************************
****  Welcome to the PDE2D 9.6 Interactive Driver  ****
*******************************************************

PDE2D can solve systems of (linear or nonlinear) steady-state,
time-dependent and eigenvalue partial differential equations
in 1D intervals, general 2D regions, and in a wide range of simple
3D regions.  Ordinary differential equation systems can also be
solved.

You will now be asked a series of interactive questions about your
problem.  The answers you give will be used to construct a PDE2D
FORTRAN program, which can then be compiled and linked with the PDE2D
runtime routines to produce an executable program.  The FORTRAN
driver program created will be well-documented and highly readable
(most of the interactive messages are repeated in the comments),
so that minor modifications or corrections can be made directly to
the FORTRAN program, without the need to work through a new
interactive session.

You can alternatively create your PDE2D FORTRAN program using the
PDE2D graphical user interface (GUI) ("pde2d_gui [progname]").  It
[RETURN]
is extraordinarily easy to set up problems using the PDE2D GUI,
which handles 0D and 1D problems, and 2D and 3D problems in "a wide
range of simple regions".  However, the PDE2D GUI cannot handle
complex regions, so if you have a complex 2D region you must use
this Interactive Driver.

If this is your first time to use PDE2D, you may want to work
through an example problem before trying one of your own.  Do you
want to work through a prepared example?
|---- Enter yes or no
yes
Several prepared examples are available.  Enter:

1 - to see a simple problem: a simply-supported elastic plate
equation, with a unit load concentrated at the midpoint of
a square.
2 - to see a more complex problem: a non-linear, steady-state
PDE, solved in an annulus.  Dirichlet (U = ...) boundary
conditions are imposed on part of the boundary, and Neumann
(dU/dn = ...) conditions are imposed on the other part, in
this example.  The initial triangulation is generated
automatically, and adaptive grid refinement is illustrated.
3 - to see an eigenvalue problem.  The region has a curved
interface across which material properties vary abruptly, in
this example.
4 - to see the first part of a thermal stress problem.  In this
part, the temperature distribution in a V-notched block is
calculated by solving the time-dependent heat conduction
equation, using adaptive time step control.
5 - to see the second part of a thermal stress problem.  In
this part, the stresses induced in the V-notched block by
thermal expansion are calculated, using the temperature
distribution output by example 4.  You must run example 4
[RETURN]
and save the tabular output before you can run example 5.
Examples 4 and 5 illustrate communication between problems.
6 - to see a 1D time-dependent integro-differential equation for
a financial math application.  In this problem there is a
term involving an integral of the solution, which requires
that we use PDE2D's feature for interpolating the solution
at the last saved time step, for use in the integral term.
7 - to see a waveguide problem (an eigenvalue problem in which
the eigenvalue appears nonlinearly).  This example shows how
to handle boundary conditions of different types on the same
arc, and how to produce a plot of a computed integral vs time.
8 - to see the Navier-Stokes equations (penalty formulation)
solved for a fluid flowing around a bend.
9 - to see a 3D elasticity problem, solved in a torus.  This
example illustrates the use of user-defined coordinate
transformations to handle more general 3D regions.
10 - to see a time-dependent wave equation (reduced to a system
of two PDEs), solved in a 3D box.
11 - to see a 3D eigenvalue problem (the Schrodinger equation
in a hydrogen atom).  This example illustrates the use of
spherical coordinates and periodic boundary conditions.
12 - to see a 3D eigenvalue problem, solved in a composite region
[RETURN]
consisting of two cylinders of different material properties.
13 - to see the axisymmetric Navier-Stokes equations solved in a
non-rectangular channel, using the collocation FEM.
14 - to see a 1D saturated/unsaturated water flow problem.
15 - to see a 1D version of the Schrodinger eigenvalue equation
of example 11.
0 - (no example)

If you select one of the examples, the correct answer for each
interactive question will be supplied after the question.
|---- Enter an integer value in the range 0 to 15
12
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ The example problem is:                                              \$
\$                                                                      \$
\$           div(D(z)*grad(U)) = lambda*U                               \$
\$                                                                      \$
\$ with U=0 on the boundary of a cylinder of radius 1 and height 2.     \$
\$ D(z) is equal to 1 in the bottom half (z<1) of the cylinder, and 5   \$
\$ in the top half.  We are looking for the eigenvalue nearest -20      \$
\$ (about -23.42).                                                      \$
\$                                                                      \$
\$ We will use cylindrical coordinates:                                 \$
\$       P1 = radius (R), P2 = polar angle (Theta), P3 = Z.             \$
\$                                                                      \$
\$ At P1=0 there is no boundary condition, there are periodic boundary  \$
\$ conditions at P2=0, 2*pi, and U=0 at P3=0, P3=2, P1=1.               \$
\$                                                                      \$
\$ Since the collocation method used by PDE2D for 3D problems does not  \$
\$ handle problems in "divergence" form, the term div(D(Z)*grad(U))     \$
\$ must be expanded, so that--in Cartesian coordinate form--the PDE     \$
\$ takes the form                                                       \$
\$                                                                      \$
\$    D*(Uxx + Uyy + Uzz) + Dz*Uz = lambda*U                            \$
[RETURN]
\$                                                                      \$
\$ There is still a problem, because Dz is infinite at the interface    \$
\$ Z=1.  We can overcome this problem by simply redefining D(Z) so      \$
\$ that it varies rapidly but continuously from D=1 to D=5 near the     \$
\$ interface:                                                           \$
\$        D = 1                           Z < 1                         \$
\$        Dz = 0                                                        \$
\$        D = 5                           Z > 1+EPS                     \$
\$        Dz = 0                                                        \$
\$        D = 1 + 4*(Z-1)/EPS             1 < Z < 1+EPS                 \$
\$        Dz = 4/EPS                                                    \$
\$ where EPS is a small number.  This approach works surprising well,   \$
\$ provided there are gridlines at Z=1 and Z=1+EPS.                     \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
[RETURN]
In what follows, when you are told to enter a 'FORTRAN expression',
this means any valid FORTRAN expression of 65 characters or less.
In this expression, you may include references to FORTRAN function
subprograms.  You may define these functions line by line at the end
of the interactive session, when prompted, or add them later using an
editor.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If you enter a "#" in the first column of any input line, this       +
+ instructs the interactive driver to read this and subsequent input   +
+ lines from the file "pde2d.in".  A "#" in the first column of an     +
+ input line in the file "pde2d.in" (or an end-of-file) instructs the  +
+ driver to switch back to interactive input.                          +
+                                                                      +
+ All lines input during an interactive session are echo printed to    +
+ a file "echo.out".  You may want to modify this file and rename it   +
+ "pde2d.in", and read some or all of your input from this file during +
+ your next interactive session.                                       +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++

PDE2D can solve problems with 0,1,2 or 3 space variables.  Enter the
dimension of your problem:
[RETURN]

0 - to solve a time-dependent ordinary differential equation system,
or an algebraic or algebraic eigenvalue system
1 - to solve problems in 1D intervals
2 - to solve problems in general 2D regions
3 - to solve problems in a wide range of simple 3D regions

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: 3                                                             \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter an integer value in the range 0 to 3
3
Is double precision mode to be used?  Double precision is recommended.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If double precision mode is used, variables and functions assigned   +
+ names beginning with a letter in the range A-H or O-Z will be DOUBLE +
+ PRECISION, and you should use double precision constants and FORTRAN +
+ expressions throughout; otherwise such variables and functions will  +
+ be of type REAL.  In either case, variables and functions assigned   +
+ names beginning with I,J,K,L,M or N will be of INTEGER type.         +
+                                                                      +
+ It is possible to convert a single precision PDE2D program to double +
+ precision after it has been created, using an editor.  Just change   +
+ all occurrences of "real" to "double precision"                      +
+                    " tdp" to "dtdp"  (note leading blank)            +
+ Any user-written code or routines must be converted "by hand", of    +
+ course.  To convert from double to single, reverse the changes.      +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: yes                                                           \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter yes or no
yes
If you don't want to read the FINE PRINT, default NPROB.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If you want to solve several similar problems in the same run, set   +
+ NPROB equal to the number of problems you want to solve.  Then NPROB +
+ loops through the main program will be done, with IPROB=1,...,NPROB, +
+ and you can make the problem parameters vary with IPROB.  NPROB      +
+ defaults to 1.                                                       +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ press [RETURN] to default NPROB                                      \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
NPROB =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

PDE2D solves the time-dependent system (note: U,F,G,U0 may be vectors,
C,RHO may be matrices):

C(X,Y,Z,T,U,Ux,Uy,Uz)*d(U)/dT =
F(X,Y,Z,T,U,Ux,Uy,Uz,Uxx,Uyy,Uzz,Uxy,Uxz,Uyz)

or the steady-state system:

F(X,Y,Z,U,Ux,Uy,Uz,Uxx,Uyy,Uzz,Uxy,Uxz,Uyz) = 0

or the linear and homogeneous eigenvalue system:

F(X,Y,Z,U,Ux,Uy,Uz,Uxx,Uyy,Uzz,Uxy,Uxz,Uyz) = lambda*RHO(X,Y,Z)*U

with boundary conditions:

G(X,Y,Z,[T],U,Ux,Uy,Uz) = 0
(periodic boundary conditions are also permitted)

For time-dependent problems there are also initial conditions:

U = U0(X,Y,Z)   at T=T0
[RETURN]

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If your PDEs involve the solution at points other than (P1,P2,P3),   +
+ the function                                                         +
+             (D)OLDSOL3(IDER,IEQ,PP1,PP2,PP3,KDEG)                    +
+ will interpolate (using interpolation of degree KDEG=1,2 or 3) to    +
+ (PP1,PP2,PP3) the function saved in UOUT(*,*,*,IDER,IEQ,ISET) on the +
+ last time step or iteration (ISET) for which it has been saved.      +
+ Thus, for example, if IDER=1, this will return the latest value of   +
+ component IEQ of the solution at (PP1,PP2,PP3), assuming this has    +
+ not been modified using UPRINT... If your equations involve          +
+ integrals of the solution, for example, you can use (D)OLDSOL3 to    +
+ approximate these using the solution from the last time step or      +
+ iteration.                                                           +
+                                                                      +
+ CAUTION: For a steady-state or eigenvalue problem, you must reset    +
+ NOUT=1 if you want to save the solution each iteration.              +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ A system of NEQN complex partial differential equations must be      +
+ written as a system of 2*NEQN real equations, by separating the      +
+ equations into their real and imaginary parts.  However, note that   +
+ the complex arithmetic abilities of FORTRAN can be used to simplify  +
[RETURN]
+ this separation.  For example, the complex PDE:                      +
+      I*(Uxx+Uyy+Uzz) - 1/(1+U**10) = 0,   where U = UR + UI*I        +
+ would be difficult to split up analytically, but using FORTRAN       +
+ expressions it is easy:                                              +
+   F1 = -(UIxx+UIyy+UIzz) -  REAL(1.0/(1.0+CMPLX(UR,UI)**10))         +
+   F2 =  (URxx+URyy+URzz) - AIMAG(1.0/(1.0+CMPLX(UR,UI)**10))         +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
You may now define global parameters, which may be referenced in any
of the "FORTRAN expressions" you input throughout the rest of this
interactive session.  You will be prompted alternately for parameter
names and their values; enter a blank name when you are finished.

Parameter names are valid FORTRAN variable names, starting in
column 1.  Thus each name consists of 1 to 6 alphanumeric characters,
the first of which must be a letter.  If the first letter is in the
range I-N, the parameter must be an integer.

Parameter values are either FORTRAN constants or FORTRAN expressions
involving only constants and global parameters defined on earlier
lines.  They may also be functions of the problem number IPROB, if
you are solving several similar problems in one run (NPROB > 1).  Note
that you are defining global CONSTANTS, not functions; e.g., parameter
[RETURN]
values may not reference any of the independent or dependent variables
of your problem.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If you define other parameters here later, using an editor, you must +
+ add them to COMMON block /PARM8Z/ everywhere this block appears, if  +
+ they are to be "global" parameters.                                  +
+                                                                      +
+ The variable PI is already included as a global parameter, with an   +
+ accurate value 3.14159...                                            +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: EPS                                                           \$
\$          0.001                                                       \$
\$      [blank line]                                                    \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
Parameter name = (type blank line to terminate)
EPS
EPS    =
|----Enter constant or FORTRAN expression-----------------------|
0.001
Parameter name = (type blank line to terminate)

If you don't want to read the FINE PRINT, enter 'no'.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ Do you want to be given a chance to write a FORTRAN block before the +
+ definitions of many functions?  If you answer 'no', you will still   +
+ be given a chance to write code before the definition of the PDE     +
+ coefficients, but not other functions.  Of course, you can always    +
+ add code later directly to the resulting program, using an editor.   +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: no                                                            \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter yes or no
no
You can solve problems in your region only if you can describe it by
X = X(P1,P2,P3)
Y = Y(P1,P2,P3)
Z = Z(P1,P2,P3)
with constant limits on the parameters P1,P2,P3.  If your region is
rectangular, enter ITRANS=0 and the trivial parameterization
X = P1
Y = P2
Z = P3
will be used.  Otherwise, you need to read the FINE PRINT below.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If P1,P2,P3 represent cylindrical, spherical or other non-Cartesian  +
+ coordinates, you can reference the Cartesian coordinates X,Y,Z       +
+ and derivatives of your unknowns with respect to these coordinates,  +
+ when you define your PDE coefficients, boundary conditions, and      +
+ volume and boundary integrals, if you enter ITRANS .NE. 0.  Enter:   +
+   ITRANS = 1, if P1,P2,P3 are cylindrical coordinates, that is, if   +
+               P1=R, P2=Theta, P3=Z, where X = R*cos(Theta)           +
+                                           Y = R*sin(Theta)           +
+                                           Z = Z                      +
+   ITRANS = -1, same as ITRANS=1, but P1=Theta, P2=R, P3=Z            +
[RETURN]
+   ITRANS = 2, if P1,P2,P3 are spherical coordinates, that is, if     +
+               P1=Rho, P2=Phi, P3=Theta, where                        +
+                                    X = Rho*sin(Phi)*cos(Theta)       +
+                                    Y = Rho*sin(Phi)*sin(Theta)       +
+                                    Z = Rho*cos(Phi)                  +
+               (Theta is longitude, Phi is measured from north pole)  +
+   ITRANS = -2, same as ITRANS=2, but P1=Rho, P2=Theta, P3=Phi        +
+   ITRANS = 3, to define your own coordinate transformation.  In this +
+               case, you will be prompted to define X,Y,Z and their   +
+               first and second derivatives in terms of P1,P2,P3.     +
+               Because of symmetry, you will not be prompted for all  +
+               of the second derivatives.  If you make a mistake in   +
+               computing any of these derivatives, PDE2D will usually +
+               be able to issue a warning message. (X1 = dX/dP1, etc) +
+   ITRANS = -3, same as ITRANS=3, but you will only be prompted to    +
+               define X,Y,Z; their first and second derivatives will  +
+               be approximated using finite differences.              +
+   When ITRANS = -3 or 3, the first derivatives of X,Y,Z must all be  +
+   continuous.                                                        +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: ITRANS = 1                                                    \$
[RETURN]
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
ITRANS =
|---- Enter an integer value in the range -3 to 3
1
A collocation finite element method is used, with tri-cubic Hermite
basis functions on the elements (small boxes) defined by the grid
points:
P1GRID(1),...,P1GRID(NP1GRID)
P2GRID(1),...,P2GRID(NP2GRID)
P3GRID(1),...,P3GRID(NP3GRID)
You will first be prompted for NP1GRID, the number of P1-grid points,
then for P1GRID(1),...,P1GRID(NP1GRID).  Any points defaulted will be
uniformly spaced between the points you define; the first and last
points cannot be defaulted.  Then you will be prompted similarly
for the number and values of the P2 and P3-grid points.  The limits
on the parameters are then:
P1GRID(1) < P1 < P1GRID(NP1GRID)
P2GRID(1) < P2 < P2GRID(NP2GRID)
P3GRID(1) < P3 < P3GRID(NP3GRID)

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ It is essential to put gridlines at Z=1 and Z=1+EPS, because there   \$
\$ are sudden changes in Dz there.                                      \$
\$                                                                      \$
\$ enter: NP1GRID = 8                                                   \$
\$        P1GRID(1) = 0                                                 \$
[RETURN]
\$        P1GRID(NP1GRID) = 1                                           \$
\$ and default the other P1GRID values                                  \$
\$        NP2GRID = 6                                                   \$
\$        P2GRID(1) = 0                                                 \$
\$        P2GRID(NP2GRID) = 2*PI                                        \$
\$ and default the other P2GRID values                                  \$
\$        NP3GRID = 8                                                   \$
\$        P3GRID(1) = 0                                                 \$
\$        P3GRID(4) = 1                                                 \$
\$        P3GRID(5) = 1+EPS                                             \$
\$        P3GRID(NP3GRID) = 2                                           \$
\$ and default the other P3GRID values                                  \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
NP1GRID =
|---- Enter an integer value in the range 1 to +INFINITY
8
P1GRID(1) =
|----Enter constant or FORTRAN expression-----------------------|
0
P1GRID(2) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P1GRID(3) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P1GRID(4) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P1GRID(5) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P1GRID(6) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P1GRID(7) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P1GRID(NP1GRID) =
|----Enter constant or FORTRAN expression-----------------------|
1
NP2GRID =
|---- Enter an integer value in the range 1 to +INFINITY
6
P2GRID(1) =
|----Enter constant or FORTRAN expression-----------------------|
0
P2GRID(2) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P2GRID(3) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P2GRID(4) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P2GRID(5) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P2GRID(NP2GRID) =
|----Enter constant or FORTRAN expression-----------------------|
2*PI
NP3GRID =
|---- Enter an integer value in the range 1 to +INFINITY
8
P3GRID(1) =
|----Enter constant or FORTRAN expression-----------------------|
0
P3GRID(2) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P3GRID(3) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P3GRID(4) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|
1
P3GRID(5) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|
1+EPS
P3GRID(6) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P3GRID(7) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P3GRID(NP3GRID) =
|----Enter constant or FORTRAN expression-----------------------|
2
If you don't want to read the FINE PRINT, enter ISOLVE = 1.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ The following linear system solvers are available:                   +
+                                                                      +
+ 1. Sparse direct method                                              +
+               Harwell Library routine MA27 (used by permission) is   +
+               used to solve the (positive definite) "normal"         +
+               equations A**T*A*x = A**T*b.  The normal equations,    +
+               which are essentially the equations which would result +
+               if a least squares finite element method were used     +
+               instead of a collocation method, are substantially     +
+               more ill-conditioned than the original system Ax = b,  +
+               so it may be important to use high precision if this   +
+               option is chosen.                                      +
+ 2. Frontal method                                                    +
+               This is an out-of-core band solver.  If you want to    +
+               override the default number of rows in the buffer (11),+
+               set a new value for NPMX8Z in the main program.        +
+ 3. Jacobi conjugate gradient iterative method                        +
+               A preconditioned conjugate gradient iterative method   +
+               is used to solve the (positive definite) normal        +
[RETURN]
+               equations.  High precision is also important if this   +
+               option is chosen.  (This solver is MPI-enhanced, if    +
+               MPI is available.)  If you want to override the        +
+               default convergence tolerance, set a new relative      +
+               tolerance CGTL8Z in the main program.                  +
+ 4. Local solver (normal equations)                                   +
+ 5. Local solver (original equations)                                 +
+               Choose these options ONLY if alterative linear system  +
+               solvers have been installed locally.  See subroutines  +
+               (D)TD3M, (D)TD3N in file (d)subs.f for instructions    +
+               on how to add local solvers.                           +
+ 6. MPI-based parallel band solver                                    +
+               This is a parallel solver which runs efficiently on    +
+               multiple processor machines, under MPI.  It is a       +
+               band solver, with the matrix distributed over the      +
+               available processors.  Choose this option ONLY if the  +
+               solver has been activated locally.  See subroutine     +
+               (D)TD3O in file (d)subs.f for instructions on how to   +
+               activate this solver and the MPI-enhancements to the   +
+               conjugate gradient solver.                             +
+                                                                      +
+ Enter ISOLVE = 1,2,3,4,5 or 6 to select a linear system solver.      +
[RETURN]
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++

If you don't want to read the FINE PRINT, enter ISOLVE = 1.
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: ISOLVE = 2                                                    \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
ISOLVE =
|---- Enter an integer value in the range 1 to 6
2
What type of PDE problem do you want to solve?

1. a steady-state (time-independent) problem
2. a time-dependent problem
3. a linear, homogeneous eigenvalue problem

Enter 1,2 or 3 to select a problem type.
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: 3                                                             \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter an integer value in the range 1 to 3
3
The shifted inverse power method will be used to find one eigenvalue
and the corresponding eigenfunction.

You can later find ALL eigenvalues (without eigenfunctions), including
complex eigenvalues, by changing ITYPE from 3 to 4 below in the FORTRAN
program.  All eigenvalues will be written to a file 'pde2d.eig'; the 50
eigenvalues closest to P8Z (P8Z is 0 by default but can be set by the
user below) will be printed and also available in the main program as
EVR8Z(k) + i*EVI8Z(k), for k=1,...,min(50,N).
+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ Caution: for ITYPE=4, the memory and computer time requirements are  +
+ much greater than for ITYPE=3, for a given grid.  However, this      +
+ calculation runs efficiently on multi-processor machines, under MPI. +
+                                                                      +
+ The calculation is also dramatically faster for symmetric 1D         +
+ Galerkin problems, and symmetric 2D Galerkin problems (IDEG=-1,-3)   +
+ because the algorithm can take advantage of the band structure of A  +
+ in finding all eigenvalues of the generalized eigenvalue problem     +
+ Az=lambda*Bz, but only when A is symmetric and B is diagonal (hence  +
+ the requirement that IDEG=-1 or -3 for 2D Galerkin problems; the RHO +
+ matrix must also be diagonal (if NEQN > 1) and of constant sign).    +
+ High precision is STRONGLY recommended in these cases.               +
[RETURN]
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
[RETURN]
If you don't want to read the FINE PRINT below, enter 'no'.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ Are your eigenvalue PDEs complex?  If 'yes', you must write each of  +
+ the unknown eigenfunctions, but NOT the eigenvalue (i.e., pretend    +
+ the eigenvalue is real even though it may not be), in terms of its   +
+ real and imaginary parts, and separate the equations into real and   +
+ imaginary parts.  Then it is assumed that your unknowns represent    +
+ alternately the real and imaginary parts of the eigenfunctions, and  +
+ that your equations represent alternately the real and imaginary     +
+ parts of the eigenvalue differential equations.  Note that your      +
+ first equation must represent exactly the real part of the first     +
+ complex PDE, your second equation must represent exactly the         +
+ imaginary part, etc.  You must not reorder the equations, nor        +
+ multiply any equation through by a constant.                         +
+                                                                      +
+ Even if your eigenvalue PDEs are real, if a desired eigenvalue/      +
+ eigenfunction is complex, you should answer 'yes' and treat the      +
+ PDEs as if they were complex, as outlined above.  If you are going   +
+ to set ITYPE=4 to find all eigenvalues without eigenfunctions,       +
+ however, you should answer 'no' even if some eigenvalues are complex.+
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
[RETURN]

If you don't want to read the FINE PRINT above, enter 'no'.

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: no                                                            \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter yes or no
no
The (shifted) inverse power method will be used to find the eigenvalue
closest to EV0R; enter a value for EV0R.  The closer you choose EV0R
to the desired eigenvalue, the faster the convergence will be.  The
default is EV0R = 0.0, that is, the smallest eigenvalue (in absolute
value) is found.
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ To find the eigenvalue nearest -20,                                  \$
\$ enter: EV0R = -20.0                                                  \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
EV0R =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|
-20.0
How many iterations (NSTEPS) of the inverse power method do you want
to do?  NSTEPS defaults to 25.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ After convergence of the inverse power method, the solution each     +
+ iteration will be a normalized eigenfunction corresponding to the    +
+ eigenvalue closest to EV0R (or EV0R+EV0I*I) and this eigenvalue will +
+ be printed.  In the FORTRAN program created by the preprocessor,     +
+ the last computed estimate of this eigenvalue will be returned as    +
+ EVLR8Z (or EVLR8Z+EVLI8Z*I), and ECON8Z will be .TRUE. if the        +
+ inverse power method has converged.                                  +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ press [RETURN] to default NSTEPS                                     \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
NSTEPS =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

How many differential equations (NEQN) are there in your problem?
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: NEQN = 1                                                      \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
NEQN =
|---- Enter an integer value in the range 1 to 99
1
You may now choose names for the component(s) of the (possibly vector)
solution U.  Each must be an alphanumeric string of one to three
characters, beginning with a letter in the range A-H or O-Z.  The
variable names X,Y,Z,P and T must not be used.  The name should
start in column 1.
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: U1 = U                                                        \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
U1 =
U
You may calculate one or more integrals (over the entire region) of
some functions of the solution and its derivatives.  How many integrals
(NINT), if any, do you want to calculate?

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ In the FORTRAN program created by the preprocessor, the computed     +
+ values of the integrals will be returned in the vector SINT8Z.  If   +
+ several iterations or time steps are done, only the last computed    +
+ values are saved in SINT8Z (all values are printed).                 +
+                                                                      +
+ A limiting value, SLIM8Z(I), for the I-th integral can be set        +
+ below in the main program.  The computations will then stop          +
+ gracefully whenever SINT8Z(I) > SLIM8Z(I), for any I=1...NINT.       +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: NINT = 0                                                      \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
NINT =
|---- Enter an integer value in the range 0 to 20
0
You may calculate one or more boundary integrals (over the entire
boundary) of some functions of the solution and its derivatives.  How
many boundary integrals (NBINT), if any, do you want to calculate?

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ In the FORTRAN program created by the preprocessor, the computed     +
+ values of the integrals will be returned in the vector BINT8Z.  If   +
+ several iterations or time steps are done, only the last computed    +
+ values are saved in BINT8Z (all values are printed).                 +
+                                                                      +
+ A limiting value, BLIM8Z(I), for the I-th boundary integral can be   +
+ set below in the main program.  The computations will then stop      +
+ gracefully whenever BINT8Z(I) > BLIM8Z(I), for any I=1...NBINT.      +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: NBINT = 0                                                     \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
NBINT =
|---- Enter an integer value in the range 0 to 20
0
Now enter FORTRAN expressions to define the PDE coefficients.
RHO may be a function of X,Y,Z, while F may be a function of

X,Y,Z,U,Ux,Uy,Uz,Uxx,Uyy,Uzz,Uxy,Uxz,Uyz

Recall that the PDE has the form

F = lambda*RHO*U

The parameters P1,P2,P3 and derivatives with respect to these may also
be referenced (U1 = dU/dP1, etc):
U1,U2,U3,U11,U22,U33,U12,U13,U23
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ The partial differential equation may be written:                    \$
\$                                                                      \$
\$      D*(Uxx + Uyy + Uzz) + Dz*Uz = lambda*1.0*U                      \$
\$                                                                      \$
\$ where D(Z) is defined to vary rapidly, but continuously, from D=1 in \$
\$ the bottom cylinder to D=5 in the top.  Now, when asked if you want  \$
\$ to write a FORTRAN block,                                            \$
\$ enter: yes                                                           \$
\$   then, when prompted, enter:                                        \$
[RETURN]
\$          IF (Z.LE.1) THEN                                            \$
\$             D = 1                                                    \$
\$             Dz = 0                                                   \$
\$          ELSE IF (Z.GE.1+EPS) THEN                                   \$
\$             D = 5                                                    \$
\$             Dz = 0                                                   \$
\$          ELSE                                                        \$
\$             D = 1 + 4.0*(Z-1)/EPS                                    \$
\$             Dz = 4.0/EPS                                             \$
\$          ENDIF                                                       \$
\$        [blank line]                                                  \$
\$   then, when prompted, enter:                                        \$
\$    F = D*(Uxx+Uyy+Uzz) + Dz*Uz                                       \$
\$    RHO = 1                                                           \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$

Do you want to write a FORTRAN block to define some parameters to be
used in the definition of these coefficients?
|---- Enter yes or no
yes
Remember to begin FORTRAN statements in column 7
|-----7-----Input FORTRAN now (type blank line to terminate)-----------|
IF (Z.LE.1) THEN
D = 1
Dz = 0
ELSE IF (Z.GE.1+EPS) THEN
D = 5
Dz = 0
ELSE
D = 1 + 4.0*(Z-1)/EPS
Dz = 4.0/EPS
ENDIF

F =
|----Enter constant or FORTRAN expression-----------------------|
D*(Uxx+Uyy+Uzz) + Dz*Uz
RHO =
|----Enter constant or FORTRAN expression-----------------------|
1
If you don't want to read the FINE PRINT, default the initial values.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ Now the initial values for the inverse power method may be defined   +
+ using FORTRAN expressions.  They may be functions of X, Y and Z      +
+ (and the parameters P1,P2,P3).                                       +
+                                                                      +
+ By default, the initial values are generated by a random number      +
+ generator.  This virtually eliminates any possibility of convergence +
+ to the wrong eigenvalue, due to an unlucky choice of initial values. +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ Press [RETURN] to default U0                                         \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
U0 =         (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

If you don't want to read the FINE PRINT, enter 'no'.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ Do you want to read the initial conditions from the restart file,    +
+ if it exists (and use the conditions supplied above if it does not   +
+ exist)?                                                              +
+                                                                      +
+ If so, PDE2D will dump the final solution at the end of each run     +
+ into a restart file "pde2d.res".  Thus the usual procedure for       +
+ using this dump/restart option is to make sure there is no restart   +
+ file in your directory left over from a previous job, then the       +
+ first time you run this job, the initial conditions supplied above   +
+ will be used, but on the second and subsequent runs the restart file +
+ from the previous run will be used to define the initial conditions. +
+                                                                      +
+ You can do all the "runs" in one program, by setting NPROB > 1.      +
+ Each pass through the DO loop, T0,TF,NSTEPS and possibly other       +
+ parameters may be varied, by making them functions of IPROB.         +
+                                                                      +
+ If the 2D or 3D collocation method is used, the coordinate           +
+ transformation should not change between dump and restart.           +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
[RETURN]
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: no                                                            \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter yes or no
no
If you do not have any periodic boundary conditions, enter IPERDC=0.

Enter IPERDC=1 for periodic conditions at P1 = P1GRID(1),P1GRID(NP1GRID)
IPERDC=2 for periodic conditions at P2 = P2GRID(1),P2GRID(NP2GRID)
IPERDC=3 for periodic conditions at P3 = P3GRID(1),P3GRID(NP3GRID)
IPERDC=4 for periodic conditions on both P1 and P2
IPERDC=5 for periodic conditions on both P1 and P3
IPERDC=6 for periodic conditions on both P2 and P3
IPERDC=7 for periodic conditions on P1, P2 and P3.
+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ When periodic boundary conditions are selected, they apply to all    +
+ variables by default.  To turn off periodic boundary conditions on   +
+ the I-th variable, set PERDC(I) to 0 (or another appropriate value   +
+ of IPERDC) below in the main program and set the desired boundary    +
+ conditions in subroutine GB8Z, "by hand".                            +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: IPERDC = 2                                                    \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
IPERDC =
|---- Enter an integer value in the range 0 to 7
2
Enter FORTRAN expressions to define the boundary condition functions,
which may be functions of

X,Y,Z,U,Ux,Uy,Uz and (if applicable) T

Recall that the boundary conditions have the form

G = 0

Enter NONE to indicate "no" boundary condition.

The parameters P1,P2,P3 and derivatives with respect to these may also
be referenced (U1 = dU/dP1, etc):
U1,U2,U3
The components (NORMx,NORMy,NORMz) of the unit outward normal vector
may also be referenced, as well as the normal derivative Unorm.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If "no" boundary condition is specified, the PDE is enforced at      +
+ points just inside the boundary (exactly on the boundary, if EPS8Z   +
+ is set to 0 in the main program).                                    +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
[RETURN]

First define the boundary conditions on the face P1 = P1GRID(1).
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: G = NONE                                                      \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
G =
|----Enter constant or FORTRAN expression-----------------------|
NONE

Now define the boundary conditions on the face P1 = P1GRID(NP1GRID).
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: G = U                                                         \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
G =
|----Enter constant or FORTRAN expression-----------------------|
U

Now define the boundary conditions on the face P2 = P2GRID(1).

IPERDC = 2, so periodic boundary conditions set automatically
[RETURN]

Now define the boundary conditions on the face P2 = P2GRID(NP2GRID).

IPERDC = 2, so periodic boundary conditions set automatically
[RETURN]

Now define the boundary conditions on the face P3 = P3GRID(1).
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: G = U                                                         \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
G =
|----Enter constant or FORTRAN expression-----------------------|
U

Now define the boundary conditions on the face P3 = P3GRID(NP3GRID).
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: G = U                                                         \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
G =
|----Enter constant or FORTRAN expression-----------------------|
U
If you don't want to read the FINE PRINT, default all of the following
variables.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ Normally, PDE2D saves the values of U,Ux,Uy,Uz at the output         +
+ points.  If different variables are to be saved (for later printing  +
+ or plotting) the following functions can be used to re-define the    +
+ output variables:                                                    +
+    define UPRINT(1) to replace  U                                    +
+           UXPRINT(1)            Ux                                   +
+           UYPRINT(1)            Uy                                   +
+           UZPRINT(1)            Uz                                   +
+ Each function may be a function of                                   +
+                                                                      +
+    X,Y,Z,U,Ux,Uy,Uz,Uxx,Uyy,Uzz,Uxy,Uxz,Uyz                          +
+                                            and (if applicable) T     +
+                                                                      +
+ Each may also be a function of the integral estimates SINT(1),...,   +
+ BINT(1),...                                                          +
+                                                                      +
+ The parameters P1,P2,P3 and derivatives with respect to these may    +
+ also be referenced (U1 = dU/dP1, etc):                               +
[RETURN]
+       U1,U2,U3,U11,U22,U33,U12,U13,U23                               +
+                                                                      +
+ The default for each variable is no change, for example, UPRINT(1)   +
+ defaults to U.  Enter FORTRAN expressions for each of the            +
+ following functions (or default).                                    +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ press [RETURN] to default all output modification variables          \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
Replace U for postprocessing?
UPRINT(1) =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

Replace Ux for postprocessing?
UXPRINT(1) =            (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

Replace Uy for postprocessing?
UYPRINT(1) =            (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

Replace Uz for postprocessing?
UZPRINT(1) =            (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

The solution is normally saved on an NP1+1 by NP2+1 by NP3+1
rectangular grid of points,
P1 = P1A + I*(P1B-P1A)/NP1,    I = 0,...,NP1
P2 = P2A + J*(P2B-P2A)/NP2,    J = 0,...,NP2
P3 = P3A + K*(P3B-P3A)/NP3,    K = 0,...,NP3
Enter values for NP1, NP2 and NP3.  Suggested values: NP1=NP2=NP3=16.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If you want to save the solution at an arbitrary user-specified set  +
+ of points, set NP2=NP3=0 and NP1+1=number of points.  In this case   +
+ you can request tabular output, but no plots can be made.            +
+                                                                      +
+ If you set NEAR8Z=1 in the main program, the values saved at each    +
+ output point will actually be the solution as evaluated at a nearby  +
+ collocation point.  For most problems this obviously will produce    +
+ less accurate output or plots, but for certain (rare) problems, a    +
+ solution component may be much less noisy when plotted only at       +
+ collocation points.                                                  +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: NP1 = 20                                                      \$
\$        NP2 = 20                                                      \$
[RETURN]
\$        NP3 = 20                                                      \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
NP1 =
|---- Enter an integer value in the range 1 to +INFINITY
20
NP2 =
|---- Enter an integer value in the range 0 to +INFINITY
20
NP3 =
|---- Enter an integer value in the range 1 to +INFINITY
20
The solution is saved on an NP1+1 by NP2+1 by NP3+1 rectangular grid
covering the box (P1A,P1B) x (P2A,P2B) x (P3A,P3B).  Enter values for
P1A,P1B,P2A,P2B,P3A,P3B.  These variables are usually defaulted.

The defaults are P1A = P1GRID(1), P1B = P1GRID(NP1GRID)
P2A = P2GRID(1), P2B = P2GRID(NP2GRID)
P3A = P3GRID(1), P3B = P3GRID(NP3GRID)

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ press [RETURN] to default P1A,P1B,P2A,P2B,P3A,P3B                    \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
P1A =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P1B =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P2A =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P2B =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P3A =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

P3B =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

To generate tabular or graphical output, choose an output option from
the list below.

0. No further output is desired
1. Table of values at output points
The tabulated output is saved in a file.
2. A plot of the contour (level) surfaces of a scalar variable.
This plot gives only a coarse overview of the solution, but is
unique in that it shows the general form of the solution in a
single picture.  The different levels are identified by color.
These plots will only reflect the true geometry if ITRANS=0.
3. Surface plot of a scalar variable, at P1, P2 or P3 = constant
cross-sections.
4. Contour plot of a scalar variable, at P1, P2 or P3 = constant
cross-sections.  These plots can be made to reflect the true
geometry of the cross-section.
5. Vector field plot, at P1, P2 or P3 = constant cross-sections.
A 3D vector field is plotted using arrows to represent the
in-plane components, with a contour plot of the out-of-plane
component superimposed.  These plots can be made to reflect
the true geometry of the cross-section.
6. One dimensional cross-sectional plots (versus P1, P2, P3 or T)
[RETURN]

Enter 0,1,2,3,4,5 or 6 to select an output option.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If you set NP2=NP3=0 and saved the solution at an arbitrary set of   +
+ user-specified output points, you can only request tabular output.   +
+                                                                      +
+ If you decide later that you want additional types of plots not      +
+ requested during this interactive session, you will have to work     +
+ through a new interactive session, so it is recommended that you     +
+ request all output or plots you think you MIGHT eventually want now, +
+ during this session.                                                 +
+                                                                      +
+ Regardless of the options you select, a dummy subroutine POSTPR      +
+ will be included in the program created by the interactive driver;   +
+ you can add your own postprocessing code to this subroutine.         +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: 3, the first time you see this message and                    \$
\$        0, the second time                                            \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter an integer value in the range 0 to 6
3
Enter a value for IVAR, to select the variable to be plotted or
printed:
IVAR = 1 means U  (possibly as modified by UPRINT,..)
2       Ux
3       Uy
4       Uz
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: IVAR = 1                                                      \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
IVAR =
|---- Enter an integer value in the range 1 to 4
1
Plots can be made at:

1. P1 = constant cross-sections
2. P2 = constant cross-sections
3. P3 = constant cross-sections

Enter 1,2 or 3 to select the cross-section type.
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: 2                                                             \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter an integer value in the range 1 to 3
2
Plots of the variable or vector as a function of P1 and P3 will be
made, at the output grid P2-points closest to
P2 = P2CROSS(1),...,P2CROSS(NP2VALS)

Enter values for NP2VALS and P2CROSS(1),...,P2CROSS(NP2VALS).
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ We want a plot of the eigenfunction at the cross-sections P2=0,PI/2, \$
\$ and PI, so                                                           \$
\$ enter: NP2VALS = 3                                                   \$
\$        P2CROSS(1) = 0                                                \$
\$        P2CROSS(2) = PI/2                                             \$
\$        P2CROSS(3) = PI                                               \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
NP2VALS =
|---- Enter an integer value in the range 1 to 100
3
P2CROSS(1) =
|----Enter constant or FORTRAN expression-----------------------|
0
P2CROSS(2) =
|----Enter constant or FORTRAN expression-----------------------|
PI/2
P2CROSS(3) =
|----Enter constant or FORTRAN expression-----------------------|
PI
Enter the view latitude, VLAT, and the view longitude, VLON, desired
for this plot, in degrees.  VLAT and VLON must be between 10 and 80
degrees; each defaults to 45 degrees.  VLAT and VLON are usually
defaulted.
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ press [RETURN] to default VLAT and VLON                              \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
VLAT =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

VLON =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|

Specify the range (UMIN,UMAX) for the dependent variable axis.  UMIN
and UMAX are often defaulted.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ By default, each plot will be scaled to just fit in the plot area.   +
+ For a common scaling, you may want to set UMIN=ALOW, UMAX=AHIGH.     +
+ ALOW and AHIGH are the minimum and maximum values over all output    +
+ points and over all saved time steps or iterations.                  +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: UMIN = ALOW                                                   \$
\$        UMAX = AHIGH                                                  \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
UMIN =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|
ALOW
UMAX =             (Press [RETURN] to default)
|----Enter constant or FORTRAN expression-----------------------|
AHIGH
Enter a title, WITHOUT quotation marks.  A maximum of 40 characters
are allowed.  The default is no title.
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: Composite of two cylinders                                    \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
TITLE =             (Press [RETURN] to default)
|----Enter title or name---------------|
Composite of two cylinders
To generate tabular or graphical output, choose an output option from
the list below.

0. No further output is desired
1. Table of values at output points
The tabulated output is saved in a file.
2. A plot of the contour (level) surfaces of a scalar variable.
This plot gives only a coarse overview of the solution, but is
unique in that it shows the general form of the solution in a
single picture.  The different levels are identified by color.
These plots will only reflect the true geometry if ITRANS=0.
3. Surface plot of a scalar variable, at P1, P2 or P3 = constant
cross-sections.
4. Contour plot of a scalar variable, at P1, P2 or P3 = constant
cross-sections.  These plots can be made to reflect the true
geometry of the cross-section.
5. Vector field plot, at P1, P2 or P3 = constant cross-sections.
A 3D vector field is plotted using arrows to represent the
in-plane components, with a contour plot of the out-of-plane
component superimposed.  These plots can be made to reflect
the true geometry of the cross-section.
6. One dimensional cross-sectional plots (versus P1, P2, P3 or T)
[RETURN]

Enter 0,1,2,3,4,5 or 6 to select an output option.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If you set NP2=NP3=0 and saved the solution at an arbitrary set of   +
+ user-specified output points, you can only request tabular output.   +
+                                                                      +
+ If you decide later that you want additional types of plots not      +
+ requested during this interactive session, you will have to work     +
+ through a new interactive session, so it is recommended that you     +
+ request all output or plots you think you MIGHT eventually want now, +
+ during this session.                                                 +
+                                                                      +
+ Regardless of the options you select, a dummy subroutine POSTPR      +
+ will be included in the program created by the interactive driver;   +
+ you can add your own postprocessing code to this subroutine.         +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: 3, the first time you see this message and                    \$
\$        0, the second time                                            \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter an integer value in the range 0 to 6
0
Do you want to define any FORTRAN function subprograms used in any of
the FORTRAN 'expressions' entered earlier, entering them line by line?

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ If you selected double precision accuracy earlier, be sure to        +
+ declare these functions and their arguments DOUBLE PRECISION.        +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: no                                                            \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter yes or no
no
If you don't want to read the FINE PRINT, enter 'no'.

+++++++++++++++ THE "FINE PRINT" (CAN USUALLY BE IGNORED) ++++++++++++++
+ Do you want to define any FORTRAN function subprograms used in any   +
+ of the FORTRAN 'expressions' entered earlier, by interpolating the   +
+ tabular output saved in a file created on an earlier PDE2D run?      +
++++++++++++++++++++++++++ END OF "FINE PRINT" +++++++++++++++++++++++++
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$ enter: no                                                            \$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$ EXAMPLE 12 \$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
|---- Enter yes or no
no
More detailed information about PDE2D can be found in the book
"Solving Partial Differential Equation Applications with PDE2D,"
Granville Sewell, John Wiley & Sons, 2018.

*******************************************
***** Input program has been created  *****
*******************************************

```