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Some basic questions about PETSC



Hi,
 
I'm still relatively new to PETSC but I've finally managed to solve my own poisson eqn using it in about a week's time.Thank you for writing such a good solver.
 
However, I have some questions still about PETSC:
 
1. Are petscscaler the same as real nos.? I am writing in double precision or real(8). So are these 2 interchangeable? (same as petscint and integer).
 
2. while linking in compaq visual fortran, I get the warning message about conflict library with LIBCMT. Is it important or can I just ignore it?
 
3. I am writing in f90 free form format. When I modify from fixed f77 format to f90, it gives me a lot of error, which seems to be the include file error. So, is it possible to write in f90 format?
 
4. I am writing a Navier stokes solver and I'm using PETSC to solve the poisson eqn. If only the RHS changes with each time step, do I need to call
 
VecCreateSeq
<insert values in RHS b>
VecAssemblyBegin
VecAssemblyEnd
VecDestroy
 
at each time step? I don't think I can (or I should) change values of b after VecAssemblyBegin,VecAssemblyEnd, or can I?
 
Thank you very much and have a nice day
 
Regards,
Ben