isw sequence

[anshulfy]

Dear all,

I am working with user element. Here are my solution commands,

Code: [Select]

BATCh
  LOOP,,1e5
    TIME,,1e-3
    PART,,1
      dt,,1e-7
      TRAN CENTRAL
      MASS, LUMP
      FORM Explicit
    PART,,2
        TANG,,1
  NEXT inter
END

I was checking the sequence of isw tasks. I see that isw=6 (i.e computing residual) is first called immediately after command TIME and then after FORM command. However, program manual says that isw=6 is called for Soln:FORM,REAC, Plot:REAC. Can someone please help me in understanding why is it called after command TIME?

Thanks,
best regards,
Anshul

[Prof. R.L. Taylor]

The residual is computed to ensure that any history variables are properly set.  This only happens for explicit solutions or the first time step. For explicit solutions it might be possible to do better, but feap was not initially intended for explicit solutions so steps are implemented primarily to ensure data is properly mapped from t_n to t_n+1.

[anshulfy]

Thanks a lot Prof. Taylor.

regards,
Anshul