299 lines
6.7 KiB
C
299 lines
6.7 KiB
C
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/* -- translated by f2c (version 19940927).
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You must link the resulting object file with the libraries:
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-lf2c -lm (in that order)
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*/
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#include "f2c.h"
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/* Subroutine */ int sgemv_(char *trans, integer *m, integer *n, real *alpha,
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real *a, integer *lda, real *x, integer *incx, real *beta, real *y,
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integer *incy)
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{
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/* System generated locals */
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integer a_dim1, a_offset, i__1, i__2;
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/* Local variables */
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static integer info;
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static real temp;
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static integer lenx, leny, i, j;
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extern logical lsame_(char *, char *);
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static integer ix, iy, jx, jy, kx, ky;
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extern /* Subroutine */ int xerbla_(char *, integer *);
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/* Purpose
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=======
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SGEMV performs one of the matrix-vector operations
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y := alpha*A*x + beta*y, or y := alpha*A'*x + beta*y,
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where alpha and beta are scalars, x and y are vectors and A is an
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m by n matrix.
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Parameters
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==========
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TRANS - CHARACTER*1.
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On entry, TRANS specifies the operation to be performed as
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follows:
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TRANS = 'N' or 'n' y := alpha*A*x + beta*y.
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TRANS = 'T' or 't' y := alpha*A'*x + beta*y.
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TRANS = 'C' or 'c' y := alpha*A'*x + beta*y.
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Unchanged on exit.
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M - INTEGER.
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On entry, M specifies the number of rows of the matrix A.
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M must be at least zero.
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Unchanged on exit.
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N - INTEGER.
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On entry, N specifies the number of columns 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 - REAL .
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On entry, ALPHA specifies the scalar alpha.
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Unchanged on exit.
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A - REAL array of DIMENSION ( LDA, n ).
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Before entry, the leading m by n part of the array A must
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contain the matrix of coefficients.
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Unchanged on exit.
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LDA - INTEGER.
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On entry, LDA specifies the first dimension of A as declared
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in the calling (sub) program. LDA must be at least
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max( 1, m ).
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Unchanged on exit.
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X - REAL array of DIMENSION at least
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( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n'
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and at least
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( 1 + ( m - 1 )*abs( INCX ) ) otherwise.
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Before entry, the incremented array X must contain the
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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 - REAL .
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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 - REAL array of DIMENSION at least
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( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n'
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and at least
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( 1 + ( n - 1 )*abs( INCY ) ) otherwise.
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Before entry with BETA non-zero, the incremented array Y
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must contain the vector y. On exit, Y is overwritten by the
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updated 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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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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Test the input parameters.
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Parameter adjustments
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Function Body */
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#define X(I) x[(I)-1]
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#define Y(I) y[(I)-1]
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#define A(I,J) a[(I)-1 + ((J)-1)* ( *lda)]
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info = 0;
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if (! lsame_(trans, "N") && ! lsame_(trans, "T") && !
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lsame_(trans, "C")) {
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info = 1;
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} else if (*m < 0) {
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info = 2;
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} else if (*n < 0) {
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info = 3;
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} else if (*lda < max(1,*m)) {
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info = 6;
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} else if (*incx == 0) {
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info = 8;
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} else if (*incy == 0) {
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info = 11;
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}
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if (info != 0) {
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xerbla_("SGEMV ", &info);
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return 0;
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}
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/* Quick return if possible. */
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if (*m == 0 || *n == 0 || *alpha == 0.f && *beta == 1.f) {
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return 0;
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}
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/* Set LENX and LENY, the lengths of the vectors x and y, and set
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up the start points in X and Y. */
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if (lsame_(trans, "N")) {
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lenx = *n;
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leny = *m;
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} else {
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lenx = *m;
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leny = *n;
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}
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if (*incx > 0) {
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kx = 1;
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} else {
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kx = 1 - (lenx - 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 - (leny - 1) * *incy;
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}
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/* Start the operations. In this version the elements of A are
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accessed sequentially with one pass through A.
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First form y := beta*y. */
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if (*beta != 1.f) {
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if (*incy == 1) {
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if (*beta == 0.f) {
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i__1 = leny;
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for (i = 1; i <= leny; ++i) {
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Y(i) = 0.f;
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/* L10: */
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}
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} else {
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i__1 = leny;
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for (i = 1; i <= leny; ++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.f) {
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i__1 = leny;
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for (i = 1; i <= leny; ++i) {
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Y(iy) = 0.f;
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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 = leny;
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for (i = 1; i <= leny; ++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.f) {
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return 0;
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}
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if (lsame_(trans, "N")) {
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/* Form y := alpha*A*x + y. */
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jx = kx;
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if (*incy == 1) {
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i__1 = *n;
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for (j = 1; j <= *n; ++j) {
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if (X(jx) != 0.f) {
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temp = *alpha * X(jx);
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i__2 = *m;
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for (i = 1; i <= *m; ++i) {
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Y(i) += temp * A(i,j);
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/* L50: */
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}
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}
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jx += *incx;
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/* L60: */
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}
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} else {
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i__1 = *n;
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for (j = 1; j <= *n; ++j) {
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if (X(jx) != 0.f) {
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temp = *alpha * X(jx);
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iy = ky;
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i__2 = *m;
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for (i = 1; i <= *m; ++i) {
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Y(iy) += temp * A(i,j);
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iy += *incy;
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/* L70: */
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}
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}
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jx += *incx;
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/* L80: */
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}
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}
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} else {
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/* Form y := alpha*A'*x + y. */
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jy = ky;
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if (*incx == 1) {
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i__1 = *n;
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for (j = 1; j <= *n; ++j) {
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temp = 0.f;
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i__2 = *m;
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for (i = 1; i <= *m; ++i) {
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temp += A(i,j) * X(i);
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/* L90: */
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}
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Y(jy) += *alpha * temp;
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jy += *incy;
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/* L100: */
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}
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} else {
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i__1 = *n;
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for (j = 1; j <= *n; ++j) {
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temp = 0.f;
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ix = kx;
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i__2 = *m;
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for (i = 1; i <= *m; ++i) {
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temp += A(i,j) * X(ix);
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ix += *incx;
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/* L110: */
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}
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Y(jy) += *alpha * temp;
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jy += *incy;
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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 SGEMV . */
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} /* sgemv_ */
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