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scscmv.c
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1/*@HEADER
2// ***********************************************************************
3//
4// Ifpack: Object-Oriented Algebraic Preconditioner Package
5// Copyright (2002) Sandia Corporation
6//
7// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
8// license for use of this work by or on behalf of the U.S. Government.
9//
10// Redistribution and use in source and binary forms, with or without
11// modification, are permitted provided that the following conditions are
12// met:
13//
14// 1. Redistributions of source code must retain the above copyright
15// notice, this list of conditions and the following disclaimer.
16//
17// 2. Redistributions in binary form must reproduce the above copyright
18// notice, this list of conditions and the following disclaimer in the
19// documentation and/or other materials provided with the distribution.
20//
21// 3. Neither the name of the Corporation nor the names of the
22// contributors may be used to endorse or promote products derived from
23// this software without specific prior written permission.
24//
25// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
26// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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30// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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37// Questions? Contact Michael A. Heroux (maherou@sandia.gov)
38//
39// ***********************************************************************
40//@HEADER
41*/
42
43void scscmv (int isym, int indexbase, int m, int n,
44 double *val, int *indx, int *pntr,
45 double *x, double *y)
46{
47 int i, j, jbgn, jend;
48
49
50/* Performs the matrix-vector operation
51
52 y = A*x
53
54 where x and y are vectors and A is a sparse matrix stored
55 in (Harwell-Boeing) compress column format. */
56
57/* --------------------------
58 First executable statement
59 -------------------------- */
60
61/* .....initialize soln */
62
63 for (i = 0; i < m; i++)
64 y[i] = 0.0;
65
66/* .....do a series of SPAXPYs (sparse saxpys) */
67
68 for (j = 0; j <n ; j++)
69 {
70 jbgn = pntr[j]-indexbase;
71 jend = pntr[j + 1]-indexbase;
72
73 for (i = jbgn; i < jend; i++)
74 {
75 y[indx[i]-indexbase] += val[i] * x[j];
76 if (indx[i]-indexbase != j && isym) y[j] += val[i]*x[indx[i]-indexbase];
77 }
78 }
79
80 return;
81} /* scscmv */
82
void scscmv(int isym, int indexbase, int m, int n, double *val, int *indx, int *pntr, double *x, double *y)
Definition: scscmv.c:43