317 lines
7.9 KiB
C
317 lines
7.9 KiB
C
/* dspmv.f -- translated by f2c (version 20100827).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#include "datatypes.h"
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/* Subroutine */ int dspmv_(char *uplo, integer *n, doublereal *alpha,
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doublereal *ap, doublereal *x, integer *incx, doublereal *beta,
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doublereal *y, integer *incy, ftnlen uplo_len)
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{
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/* System generated locals */
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integer i__1, i__2;
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/* Local variables */
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integer i__, j, k, kk, ix, iy, jx, jy, kx, ky, info;
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doublereal temp1, temp2;
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extern logical lsame_(char *, char *, ftnlen, ftnlen);
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extern /* Subroutine */ int xerbla_(char *, integer *, ftnlen);
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/* .. Scalar Arguments .. */
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/* .. */
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/* .. Array Arguments .. */
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/* .. */
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/* Purpose */
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/* ======= */
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/* DSPMV performs the matrix-vector operation */
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/* y := alpha*A*x + beta*y, */
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/* where alpha and beta are scalars, x and y are n element vectors and */
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/* A is an n by n symmetric matrix, supplied in packed form. */
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/* Arguments */
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/* ========== */
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/* UPLO - CHARACTER*1. */
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/* On entry, UPLO specifies whether the upper or lower */
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/* triangular part of the matrix A is supplied in the packed */
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/* array AP as follows: */
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/* UPLO = 'U' or 'u' The upper triangular part of A is */
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/* supplied in AP. */
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/* UPLO = 'L' or 'l' The lower triangular part of A is */
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/* supplied in AP. */
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/* Unchanged on exit. */
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/* N - INTEGER. */
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/* On entry, N specifies the order of the matrix A. */
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/* N must be at least zero. */
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/* Unchanged on exit. */
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/* ALPHA - DOUBLE PRECISION. */
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/* On entry, ALPHA specifies the scalar alpha. */
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/* Unchanged on exit. */
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/* AP - DOUBLE PRECISION array of DIMENSION at least */
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/* ( ( n*( n + 1 ) )/2 ). */
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/* Before entry with UPLO = 'U' or 'u', the array AP must */
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/* contain the upper triangular part of the symmetric matrix */
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/* packed sequentially, column by column, so that AP( 1 ) */
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/* contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 ) */
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/* and a( 2, 2 ) respectively, and so on. */
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/* Before entry with UPLO = 'L' or 'l', the array AP must */
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/* contain the lower triangular part of the symmetric matrix */
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/* packed sequentially, column by column, so that AP( 1 ) */
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/* contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 ) */
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/* and a( 3, 1 ) respectively, and so on. */
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/* Unchanged on exit. */
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/* X - DOUBLE PRECISION array of dimension at least */
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/* ( 1 + ( n - 1 )*abs( INCX ) ). */
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/* Before entry, the incremented array X must contain the n */
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/* element vector x. */
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/* Unchanged on exit. */
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/* INCX - INTEGER. */
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/* On entry, INCX specifies the increment for the elements of */
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/* X. INCX must not be zero. */
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/* Unchanged on exit. */
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/* BETA - DOUBLE PRECISION. */
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/* On entry, BETA specifies the scalar beta. When BETA is */
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/* supplied as zero then Y need not be set on input. */
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/* Unchanged on exit. */
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/* Y - DOUBLE PRECISION array of dimension at least */
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/* ( 1 + ( n - 1 )*abs( INCY ) ). */
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/* Before entry, the incremented array Y must contain the n */
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/* element vector y. On exit, Y is overwritten by the updated */
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/* vector y. */
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/* INCY - INTEGER. */
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/* On entry, INCY specifies the increment for the elements of */
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/* Y. INCY must not be zero. */
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/* Unchanged on exit. */
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/* Further Details */
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/* =============== */
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/* Level 2 Blas routine. */
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/* -- Written on 22-October-1986. */
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/* Jack Dongarra, Argonne National Lab. */
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/* Jeremy Du Croz, Nag Central Office. */
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/* Sven Hammarling, Nag Central Office. */
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/* Richard Hanson, Sandia National Labs. */
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/* ===================================================================== */
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/* .. Parameters .. */
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/* .. */
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/* .. Local Scalars .. */
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/* .. */
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/* .. External Functions .. */
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/* .. */
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/* .. External Subroutines .. */
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/* .. */
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/* Test the input parameters. */
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/* Parameter adjustments */
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--y;
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--x;
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--ap;
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/* Function Body */
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info = 0;
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if (! lsame_(uplo, "U", (ftnlen)1, (ftnlen)1) && ! lsame_(uplo, "L", (
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ftnlen)1, (ftnlen)1)) {
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info = 1;
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} else if (*n < 0) {
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info = 2;
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} else if (*incx == 0) {
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info = 6;
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} else if (*incy == 0) {
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info = 9;
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}
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if (info != 0) {
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xerbla_("DSPMV ", &info, (ftnlen)6);
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return 0;
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}
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/* Quick return if possible. */
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if (*n == 0 || (*alpha == 0. && *beta == 1.)) {
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return 0;
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}
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/* Set up the start points in X and Y. */
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if (*incx > 0) {
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kx = 1;
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} else {
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kx = 1 - (*n - 1) * *incx;
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}
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if (*incy > 0) {
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ky = 1;
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} else {
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ky = 1 - (*n - 1) * *incy;
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}
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/* Start the operations. In this version the elements of the array AP */
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/* are accessed sequentially with one pass through AP. */
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/* First form y := beta*y. */
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if (*beta != 1.) {
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if (*incy == 1) {
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if (*beta == 0.) {
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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y[i__] = 0.;
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/* L10: */
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}
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} else {
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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y[i__] = *beta * y[i__];
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/* L20: */
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}
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}
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} else {
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iy = ky;
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if (*beta == 0.) {
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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y[iy] = 0.;
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iy += *incy;
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/* L30: */
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}
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} else {
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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y[iy] = *beta * y[iy];
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iy += *incy;
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/* L40: */
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}
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}
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}
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}
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if (*alpha == 0.) {
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return 0;
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}
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kk = 1;
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if (lsame_(uplo, "U", (ftnlen)1, (ftnlen)1)) {
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/* Form y when AP contains the upper triangle. */
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if (*incx == 1 && *incy == 1) {
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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temp1 = *alpha * x[j];
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temp2 = 0.;
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k = kk;
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i__2 = j - 1;
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for (i__ = 1; i__ <= i__2; ++i__) {
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y[i__] += temp1 * ap[k];
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temp2 += ap[k] * x[i__];
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++k;
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/* L50: */
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}
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y[j] = y[j] + temp1 * ap[kk + j - 1] + *alpha * temp2;
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kk += j;
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/* L60: */
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}
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} else {
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jx = kx;
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jy = ky;
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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temp1 = *alpha * x[jx];
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temp2 = 0.;
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ix = kx;
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iy = ky;
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i__2 = kk + j - 2;
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for (k = kk; k <= i__2; ++k) {
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y[iy] += temp1 * ap[k];
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temp2 += ap[k] * x[ix];
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ix += *incx;
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iy += *incy;
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/* L70: */
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}
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y[jy] = y[jy] + temp1 * ap[kk + j - 1] + *alpha * temp2;
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jx += *incx;
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jy += *incy;
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kk += j;
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/* L80: */
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}
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}
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} else {
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/* Form y when AP contains the lower triangle. */
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if (*incx == 1 && *incy == 1) {
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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temp1 = *alpha * x[j];
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temp2 = 0.;
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y[j] += temp1 * ap[kk];
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k = kk + 1;
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i__2 = *n;
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for (i__ = j + 1; i__ <= i__2; ++i__) {
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y[i__] += temp1 * ap[k];
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temp2 += ap[k] * x[i__];
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++k;
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/* L90: */
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}
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y[j] += *alpha * temp2;
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kk += *n - j + 1;
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/* L100: */
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}
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} else {
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jx = kx;
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jy = ky;
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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temp1 = *alpha * x[jx];
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temp2 = 0.;
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y[jy] += temp1 * ap[kk];
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ix = jx;
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iy = jy;
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i__2 = kk + *n - j;
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for (k = kk + 1; k <= i__2; ++k) {
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ix += *incx;
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iy += *incy;
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y[iy] += temp1 * ap[k];
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temp2 += ap[k] * x[ix];
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/* L110: */
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}
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y[jy] += *alpha * temp2;
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jx += *incx;
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jy += *incy;
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kk += *n - j + 1;
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/* L120: */
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}
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}
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}
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return 0;
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/* End of DSPMV . */
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} /* dspmv_ */
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