Hi Satish,

Thanks for your answer. In the attached program, I have declared the following standard fortran arrays: real(dp),dimension(:,:),allocatable :: D1X,D2X,D1Y,D2Y
Let's say these are real matrix derivatives that I need to insert in my complex A matrix (it could also be some real baseflow from a similarity solver). I have filled D1Y with 999.d0 just to test (see line 169). Then I insert D1Y in the global (complex) matrix with call MatSetValues(A,ny,idxm2,ny,idxn2,D1Y,INSERT_VALUES,ierr). I expected that in the Matrix A, this would be automatically converted to 999.0 + 0.0i but when I view A, I see 999 + 999 i or even 999 + 1.0326e-321 i. Is there a way to insert D1Y as is and obtain the proper behavior? How would you do it?

Thanks

Anthony

On Fri, Jun 19, 2015 at 11:08 AM, Satish Balay <balay@mcs.anl.gov> wrote:
On Fri, 19 Jun 2015, Anthony Haas wrote:

> Hi,
>
> I have a Fortran90 program that solves a complex linear generalized eigenvalue
> problem (GEVP) using standard fortran 90 programming:
>
> Subroutines, modules, allocatable arrays, real(8), int,...
>
> This program uses Lapack to solve the GEVP. The program is mainly made off:
>
> 1) set dimensions of problem and initialize arrays,...
> 2) compute the baseflow (for instance boundary layer flow)
> 3) build the (stability) complex generalized eigenvalue problem ==> build
> (dense) matrices A and B
> 4) solve the GEVP with Lapack
>
> Now I want to use PETSc + SLEPc to use sparse matrices. Do I need to
> rewrite/modify everything in terms of PETSc variables as follows:
>
> - int -> PetscInt
> - real(8) -> PetscScalar
perhaps you mean: PetscReal

> - complex*16 -> PetscScalar
>
> or is it possible to reuse all that F90 code? For instance I have a similarity
> solver that computes Blasius solution. If that similarity solver provides me
> with u and v velocities in terms of standard fortran90 real(8) variables, how
> should I do to use these variables to build my complex matrix? Should I
> convert them to Petsc variables? How?
>

You can use the current datatypes used in your code - And always make
sure the types match manually. [Fortran does not have typecheck anyway..]

> what should I do with my Fortran90 allocatable arrays?
>
> real(dp),allocatable,dimension(:,:) :: u-->
> PetscScalar,allocatable,dimension(:,:) :: u ????

Either should work.

You can add the following to your code:

#if !defined(PETSC_USE_COMPLEX)
#error "this code requires PETSc --with-scalar-type=complex build"
#endif
#if !defined(PETSC_USE_REAL_DOUBLE)
#error "this code requires PETSc --with-precision=real build"
#endif

Satish