Sorry - I should have checked the code closer. [real(dp) vs PetscScalar] MatSetValues() expects PetscScalar. You cannot pass in 'real*8' in place of 'complex*16' [i.e PetscScalar] - and expect it to work. This is what I meat by 'make sure the types match manually' You'll have to convert real*8 to complex*16 yourself before calling MatSetValues(). Satish On Fri, 19 Jun 2015, Anthony Paul Haas wrote:

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 <[email protected]> wrote:

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On Fri, 19 Jun 2015, Anthony Haas wrote:

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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..]

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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