Actual source code: fmult.F90

  1: !
  2: !
  3: !    Fortran kernel for sparse matrix-vector product in the AIJ matrix format
  4: !
  5: #include <petsc/finclude/petscsys.h>
  6: !
  7:       subroutine FortranMultTransposeAddAIJ(n,x,ii,jj,a,y)
  8:       implicit none
  9:       PetscScalar x(0:*),a(0:*),y(0:*)
 10:       PetscScalar alpha
 11:       PetscInt    n,ii(*),jj(0:*)

 13:       PetscInt    i,j,jstart,jend

 15:       jend  = ii(1)
 16:       do 10,i=1,n
 17:         jstart = jend
 18:         jend   = ii(i+1)
 19:         alpha  = x(i-1)
 20:         do 20 j=jstart,jend-1
 21:           y(jj(j)) = y(jj(j)) + alpha*a(j)
 22:  20     continue
 23:  10   continue

 25:       end

 27:       subroutine FortranMultAIJ(n,x,ii,jj,a,y)
 28:       implicit none
 29:       PetscScalar x(0:*),a(0:*),y(*)
 30:       PetscInt    n,ii(*),jj(0:*)

 32:       PetscInt i,j,jstart,jend
 33:       PetscScalar  sum

 35:       jend  = ii(1)
 36:       do 10,i=1,n
 37:         jstart = jend
 38:         jend   = ii(i+1)
 39:         sum    = 0.d0
 40:         do 20 j=jstart,jend-1
 41:           sum = sum + a(j)*x(jj(j))
 42:  20     continue
 43:         y(i) = sum
 44:  10   continue

 46:       end