If one calls KSPSolveTranspose, how does PETSc actually do the solve? Does it simply use the transpose of the pre-computed preconditioner as the preconditioner for the Transpose solve, or does it recompute the ILU of the transpose matrix? I suspect they are not the same.
As posted in earlier emails, the preconditioned and true residual numbers don't seem correct to me, but the results are fine (I have other ways to check the results). I've tried taking the transpose of the matrix within my Fortran code, but I'm not quite sure how to get this to work. It requires passing of a NULL pointer, but it's not clear how to do this in Fortran. What I would like to do is to get the transpose of my matrix within my code, and then do a KSPSolve on that to confirm whether the residual numbers I'm getting from KSPSolveTranspose are correct. Any pointers on doing this would be appreciated. Randy -- Randall Mackie GSY-USA, Inc. PMB# 643 2261 Market St., San Francisco, CA 94114-1600 Tel (415) 469-8649 Fax (415) 469-5044 California Registered Geophysicist License No. GP 1034
