Actual source code: fmultadd.F

  1: !
  2: !  "$Id: fmultadd.F,v 1.12 2001/08/07 03:05:24 balay Exp $";
  3: !
  4: !    Fortran kernel for sparse matrix-vector product in the AIJ format
  5: !
 6:  #include include/finclude/petscdef.h
  7: !
  8:       subroutine FortranMultAddAIJ(n,x,ii,jj,a,y,z)
  9:       implicit none
 10:       PetscScalar      x(0:*),a(0:*),y(*),z(*)
 11:       integer          n,ii(*),jj(0:*)

 13:       integer i,j,jstart,jend
 14:       PetscScalar  sum

 16:       jend  = ii(1)
 17:       do 10,i=1,n
 18:         jstart = jend
 19:         jend   = ii(i+1)
 20:         sum    = y(i)
 21:         do 20 j=jstart,jend-1
 22:           sum = sum + a(j)*x(jj(j))
 23:  20     continue
 24:         z(i) = sum
 25:  10   continue

 27:       return
 28:       end