xref: /petsc/src/mat/utils/axpy.c (revision dbb450ca0a1bd4568a196678f20f5151425d3a04)
16f79c3a4SBarry Smith #ifndef lint
2*dbb450caSBarry Smith static char vcid[] = "$Id: axpy.c,v 1.8 1995/08/22 16:32:04 bsmith Exp bsmith $";
36f79c3a4SBarry Smith #endif
46f79c3a4SBarry Smith 
548b35521SBarry Smith #include "matimpl.h"  /*I   "mat.h"  I*/
66f79c3a4SBarry Smith 
706be10caSBarry Smith /*@
806be10caSBarry Smith    MatAXPY - Y = a*X + Y
96f79c3a4SBarry Smith 
106f79c3a4SBarry Smith    Input Parameters:
1106be10caSBarry Smith .  X,Y - the matrices
1206be10caSBarry Smith .  a - the scalar multiple
136f79c3a4SBarry Smith 
1406be10caSBarry Smith .keywods: Mat, add
1506be10caSBarry Smith  @*/
1606be10caSBarry Smith int MatAXPY(Scalar *a,Mat X,Mat Y)
176f79c3a4SBarry Smith {
1806be10caSBarry Smith   int    m1,m2,n1,n2,i,*row,start,end,j,ncols,ierr;
1906be10caSBarry Smith   Scalar *val,*vals;
206f79c3a4SBarry Smith 
211a941147SBarry Smith   PETSCVALIDHEADERSPECIFIC(X,MAT_COOKIE);  PETSCVALIDHEADERSPECIFIC(Y,MAT_COOKIE);
2206be10caSBarry Smith   MatGetSize(X,&m1,&n1);  MatGetSize(X,&m2,&n2);
23bbb6d6a8SBarry Smith   if (m1 != m2 || n1 != n2) SETERRQ(1,"MatAXPY:Non conforming matrix add");
2478b31e54SBarry Smith   vals = (Scalar *) PETSCMALLOC( n1*sizeof(Scalar) ); CHKPTRQ(vals);
2506be10caSBarry Smith   MatGetOwnershipRange(X,&start,&end);
2606be10caSBarry Smith   for ( i=start; i<end; i++ ) {
2706be10caSBarry Smith     MatGetRow(X,i,&ncols,&row,&val);
2806be10caSBarry Smith     for ( j=0; j<ncols; j++ ) {
2906be10caSBarry Smith       vals[j] = (*a)*val[j];
306f79c3a4SBarry Smith     }
31*dbb450caSBarry Smith     ierr = MatSetValues(Y,1,&i,ncols,row,vals,ADD_VALUES); CHKERRQ(ierr);
3206be10caSBarry Smith     MatRestoreRow(X,i,&ncols,&row,&val);
336f79c3a4SBarry Smith   }
3478b31e54SBarry Smith   PETSCFREE(vals);
3578b31e54SBarry Smith   ierr = MatAssemblyBegin(Y,FINAL_ASSEMBLY); CHKERRQ(ierr);
3678b31e54SBarry Smith   ierr = MatAssemblyEnd(Y,FINAL_ASSEMBLY); CHKERRQ(ierr);
376f79c3a4SBarry Smith   return 0;
386f79c3a4SBarry Smith }
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