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Keyword type: prestep (*RESTART,READ), step (*RESTART,WRITE)
Sometimes you wish to continue a previous run without having to redo the complete calculation. This is where the *RESTART keyword comes in. It can be used to store results for a later restart, or to continue a previous calculation.
There is one required parameter specifying whether you want to read previous results (READ) or store the results of the present calculation for future restarts (WRITE). This parameter must follow immediately after the *RESTART keyword card.
If you specify READ, you can indicate with the parameter STEP which step of the previous run is to be read. The results will be read from the binary file “jobname.rin” which should have been generated in a previous run. If the STEP parameter is absent the last step stored in the restart file is taken. A restart file can contain any number of steps and anything which is allowed within a step. For instance, one can define new loads based on sets generated in previous runs. If present, the *RESTART,READ line must be the first non-comment line in the input deck.
If you specify WRITE, you can specify the frequency (parameter FREQUENCY) at which results are stored. A frequency of two means that the results of every second step will be stored. Default is one. The results will be stored in binary format in file “jobname.rout”. Any existing file with this name will be deleted prior to the first writing operation. The restart file is being written starting with the step in which the *RESTART card appears and is being continued up to the step in which the *RESTART card is reused, if any. A reuse of the *RESTART card can be useful in case the user does not want any further steps to be stored in the restart file (FREQUENCY=0), or in case he/she wants to change the write frequency.
In order to prevent the restart file to be come too big, the user can specify the parameter OVERLAY for the *RESTART,WRITE combination. In that case every new step being written to the restart file will delete all previous information. So only the last step written to file will be available for any subsequent reuse by a *RESTART,READ command.
For a subsequent restart job with name “jobname_new.inp” the “jobname.rout” file must be renamed into “jobname_new.rin”. The *RESTART,WRITE combination must be used within a *STEP definition
First and only line:
Example: *RESTART,READ,STEP=2
will read the results of step two in the previous calculation.
Example: *RESTART,WRITE,FREQUENCY=3
will write the results every third step.
Example files: beamread, beamwrite, beamread2, beamwrite2.