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Subroutine SOLTIM
March 1996
11.3.3
USER,IUSER In these arrays information concerning the coefficients etc. must be stored. Consult the manual ”Standard Problems” for the actual filling of these arrays.
When the user uses elements with type numbers smaller than 99, he may fill IUSER and
USER in his own way.
IUSER and USER are variable length arrays and should be dimensioned properly. Their first
positions must be filled by the user.
Common Blocks
Besides the parameters in the parameter list, SOLTIM uses also the common block CTIMEN to
control the time integration:
COMMON /CTIMEN/ T, TOUT, TSTEP, TEND, T0, RTIME(5), IFLAG, ICONS, ITIMDEP, ITIME(7)
Common block CTIMEN must be submitted by the user to the main program. Meaning of the
parameters in CTIMEN:
T Actual time. At input (in the main program) the user should set T equal to the initial time.
TOUT The integration is performed from initial time to TOUT. When TOUT is reached control
is returned to the main program. The user must give TOUT a value in the main program.
TSTEP Time step for the numerical integration. The time-step may be chosen by the user
(ICHTIM = 5 to 8) or by the subroutine. The user may change his own chosen time-step in
subroutine FILTIM.
TEND End time of integration. When TEND is reached control is returned to the main program,
but also all memory used by SOLTIM is released. Restart is not possible for t > TEND. The
user must give TEND a value in the main program.
T0 Initial time for the first integration step. T0 = t0 . The user must give T0 a value before the
first call of SOLTIM in a series of calls of SOLTIM.
RTIME Dummy real array of length 5. This array is not yet used, but must be positioned in the
common block
IFLAG Error indicator. When IFLAG = 3 at the output, the process has been terminated succesfully; if IFLAG = 4 the integration process has been stopped due to errors or inaccuracy.
This may for example be the case if a discontinuity is present in the solution.
ICONS Indication if the matrices M and S as well as the time-step TSTEP are constant (ICONS=1)
or not (ICONS=0). ICONS=1 might result in a faster program in the case of a constant stepsize algorithm.
ITIMDEP This parameter is used to indicate if a the solution is time-dependent (1) or not (0).
This is the only parameter that gets a value by the SEPRAN starting subroutines. Subroutine
SOLTIM changes this value to 1.
ITIME Dummy integer array of length 7. This array is not yet used, but must be positioned in
the common block
Mark that the parameters in CTIMEN are not initialized by SEPRAN subroutines, except ITIMDEP.
However, some of the parameters may get a value by subroutine SOLTIM. All other ones must be
initialized by the user himself! Input
The parameters ITYTIM, ICHTIM and EPSUSR must have a value.
The parameters T, TOUT, TEND, T0 and if necessary TSTEP must have a value.
The arrays KMESH, KPROB, INTMAT and ISOL must have been filled.
If necessary the arrays IUSER and USER must have been filled.