[petsc-users] BiCGSTAB for general use

[Hong Zhang]

Paul :

Is your matrix A dense or sparse?
Petsc is a powerful tool for solving Ax=b with sparse matrix A.
When A is dense, petsc supports wrapper to LAPACK (sequential) and
PLAPACK (parallel).

I would suggest read petsc user manual, and test
~petsc/src/ksp/ksp/examples/tutorials/ex1.c, ex2.c ...
then replace matrix and rhs vector with yours.

Hong
>
> I am attempting to solve a large, dense equation system. I would like to try using the BiCGSTAB algorithm, and specifically, the petsc library, as it is open source and seems to be well supported. I take it petsc is primarily aimed at people solving partial differential equations by 'brute force' type methods. In my case, I would like to either
> 1) supply my A and b in Ax = b, and have a library solve it (LU factorization from LAPACK works, but it's slow) or
> 2) supply matrix products A times a vector (this is what is used internally in BiCGSTAB), the right hand side
> If necessary, I have a decent idea for a solution guess for the first iteration.
>
> So my questions are:
> 1) Is it feasible, and reasonably convenient, to use petsc for this purpose?
> 2) If so, is there a good example/tutorial/pseudocode somewhere online, or on the mailinglist, for my use case? I have been reading the petsc examples, but they are somewhat tough to follow for a complete petsc beginner. Also, they seem to apply primarily to PDE solving.
>
> I am using the Fortran 90/95 language.
>
> Best regards
> Paul
>
>