256 lines
7.2 KiB
C
256 lines
7.2 KiB
C
#include "blaswrap.h"
|
|
#ifdef _cpluscplus
|
|
extern "C" {
|
|
#endif
|
|
#include "f2c.h"
|
|
|
|
/* Subroutine */ int dsymv_(char *uplo, integer *n, doublereal *alpha,
|
|
doublereal *a, integer *lda, doublereal *x, integer *incx, doublereal
|
|
*beta, doublereal *y, integer *incy)
|
|
{
|
|
/* System generated locals */
|
|
integer a_dim1, a_offset, i__1, i__2;
|
|
/* Local variables */
|
|
static integer info;
|
|
static doublereal temp1, temp2;
|
|
static integer i__, j;
|
|
extern logical lsame_(char *, char *);
|
|
static integer ix, iy, jx, jy, kx, ky;
|
|
extern /* Subroutine */ int xerbla_(char *, integer *);
|
|
#define a_ref(a_1,a_2) a[(a_2)*a_dim1 + a_1]
|
|
/* Purpose
|
|
=======
|
|
DSYMV performs the matrix-vector operation
|
|
y := alpha*A*x + beta*y,
|
|
where alpha and beta are scalars, x and y are n element vectors and
|
|
A is an n by n symmetric matrix.
|
|
Parameters
|
|
==========
|
|
UPLO - CHARACTER*1.
|
|
On entry, UPLO specifies whether the upper or lower
|
|
triangular part of the array A is to be referenced as
|
|
follows:
|
|
UPLO = 'U' or 'u' Only the upper triangular part of A
|
|
is to be referenced.
|
|
UPLO = 'L' or 'l' Only the lower triangular part of A
|
|
is to be referenced.
|
|
Unchanged on exit.
|
|
N - INTEGER.
|
|
On entry, N specifies the order of the matrix A.
|
|
N must be at least zero.
|
|
Unchanged on exit.
|
|
ALPHA - DOUBLE PRECISION.
|
|
On entry, ALPHA specifies the scalar alpha.
|
|
Unchanged on exit.
|
|
A - DOUBLE PRECISION array of DIMENSION ( LDA, n ).
|
|
Before entry with UPLO = 'U' or 'u', the leading n by n
|
|
upper triangular part of the array A must contain the upper
|
|
triangular part of the symmetric matrix and the strictly
|
|
lower triangular part of A is not referenced.
|
|
Before entry with UPLO = 'L' or 'l', the leading n by n
|
|
lower triangular part of the array A must contain the lower
|
|
triangular part of the symmetric matrix and the strictly
|
|
upper triangular part of A is not referenced.
|
|
Unchanged on exit.
|
|
LDA - INTEGER.
|
|
On entry, LDA specifies the first dimension of A as declared
|
|
in the calling (sub) program. LDA must be at least
|
|
max( 1, n ).
|
|
Unchanged on exit.
|
|
X - DOUBLE PRECISION array of dimension at least
|
|
( 1 + ( n - 1 )*abs( INCX ) ).
|
|
Before entry, the incremented array X must contain the n
|
|
element vector x.
|
|
Unchanged on exit.
|
|
INCX - INTEGER.
|
|
On entry, INCX specifies the increment for the elements of
|
|
X. INCX must not be zero.
|
|
Unchanged on exit.
|
|
BETA - DOUBLE PRECISION.
|
|
On entry, BETA specifies the scalar beta. When BETA is
|
|
supplied as zero then Y need not be set on input.
|
|
Unchanged on exit.
|
|
Y - DOUBLE PRECISION array of dimension at least
|
|
( 1 + ( n - 1 )*abs( INCY ) ).
|
|
Before entry, the incremented array Y must contain the n
|
|
element vector y. On exit, Y is overwritten by the updated
|
|
vector y.
|
|
INCY - INTEGER.
|
|
On entry, INCY specifies the increment for the elements of
|
|
Y. INCY must not be zero.
|
|
Unchanged on exit.
|
|
Level 2 Blas routine.
|
|
-- Written on 22-October-1986.
|
|
Jack Dongarra, Argonne National Lab.
|
|
Jeremy Du Croz, Nag Central Office.
|
|
Sven Hammarling, Nag Central Office.
|
|
Richard Hanson, Sandia National Labs.
|
|
Test the input parameters.
|
|
Parameter adjustments */
|
|
a_dim1 = *lda;
|
|
a_offset = 1 + a_dim1 * 1;
|
|
a -= a_offset;
|
|
--x;
|
|
--y;
|
|
/* Function Body */
|
|
info = 0;
|
|
if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) {
|
|
info = 1;
|
|
} else if (*n < 0) {
|
|
info = 2;
|
|
} else if (*lda < max(1,*n)) {
|
|
info = 5;
|
|
} else if (*incx == 0) {
|
|
info = 7;
|
|
} else if (*incy == 0) {
|
|
info = 10;
|
|
}
|
|
if (info != 0) {
|
|
xerbla_("DSYMV ", &info);
|
|
return 0;
|
|
}
|
|
/* Quick return if possible. */
|
|
if (*n == 0 || *alpha == 0. && *beta == 1.) {
|
|
return 0;
|
|
}
|
|
/* Set up the start points in X and Y. */
|
|
if (*incx > 0) {
|
|
kx = 1;
|
|
} else {
|
|
kx = 1 - (*n - 1) * *incx;
|
|
}
|
|
if (*incy > 0) {
|
|
ky = 1;
|
|
} else {
|
|
ky = 1 - (*n - 1) * *incy;
|
|
}
|
|
/* Start the operations. In this version the elements of A are
|
|
accessed sequentially with one pass through the triangular part
|
|
of A.
|
|
First form y := beta*y. */
|
|
if (*beta != 1.) {
|
|
if (*incy == 1) {
|
|
if (*beta == 0.) {
|
|
i__1 = *n;
|
|
for (i__ = 1; i__ <= i__1; ++i__) {
|
|
y[i__] = 0.;
|
|
/* L10: */
|
|
}
|
|
} else {
|
|
i__1 = *n;
|
|
for (i__ = 1; i__ <= i__1; ++i__) {
|
|
y[i__] = *beta * y[i__];
|
|
/* L20: */
|
|
}
|
|
}
|
|
} else {
|
|
iy = ky;
|
|
if (*beta == 0.) {
|
|
i__1 = *n;
|
|
for (i__ = 1; i__ <= i__1; ++i__) {
|
|
y[iy] = 0.;
|
|
iy += *incy;
|
|
/* L30: */
|
|
}
|
|
} else {
|
|
i__1 = *n;
|
|
for (i__ = 1; i__ <= i__1; ++i__) {
|
|
y[iy] = *beta * y[iy];
|
|
iy += *incy;
|
|
/* L40: */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if (*alpha == 0.) {
|
|
return 0;
|
|
}
|
|
if (lsame_(uplo, "U")) {
|
|
/* Form y when A is stored in upper triangle. */
|
|
if (*incx == 1 && *incy == 1) {
|
|
i__1 = *n;
|
|
for (j = 1; j <= i__1; ++j) {
|
|
temp1 = *alpha * x[j];
|
|
temp2 = 0.;
|
|
i__2 = j - 1;
|
|
for (i__ = 1; i__ <= i__2; ++i__) {
|
|
y[i__] += temp1 * a_ref(i__, j);
|
|
temp2 += a_ref(i__, j) * x[i__];
|
|
/* L50: */
|
|
}
|
|
y[j] = y[j] + temp1 * a_ref(j, j) + *alpha * temp2;
|
|
/* L60: */
|
|
}
|
|
} else {
|
|
jx = kx;
|
|
jy = ky;
|
|
i__1 = *n;
|
|
for (j = 1; j <= i__1; ++j) {
|
|
temp1 = *alpha * x[jx];
|
|
temp2 = 0.;
|
|
ix = kx;
|
|
iy = ky;
|
|
i__2 = j - 1;
|
|
for (i__ = 1; i__ <= i__2; ++i__) {
|
|
y[iy] += temp1 * a_ref(i__, j);
|
|
temp2 += a_ref(i__, j) * x[ix];
|
|
ix += *incx;
|
|
iy += *incy;
|
|
/* L70: */
|
|
}
|
|
y[jy] = y[jy] + temp1 * a_ref(j, j) + *alpha * temp2;
|
|
jx += *incx;
|
|
jy += *incy;
|
|
/* L80: */
|
|
}
|
|
}
|
|
} else {
|
|
/* Form y when A is stored in lower triangle. */
|
|
if (*incx == 1 && *incy == 1) {
|
|
i__1 = *n;
|
|
for (j = 1; j <= i__1; ++j) {
|
|
temp1 = *alpha * x[j];
|
|
temp2 = 0.;
|
|
y[j] += temp1 * a_ref(j, j);
|
|
i__2 = *n;
|
|
for (i__ = j + 1; i__ <= i__2; ++i__) {
|
|
y[i__] += temp1 * a_ref(i__, j);
|
|
temp2 += a_ref(i__, j) * x[i__];
|
|
/* L90: */
|
|
}
|
|
y[j] += *alpha * temp2;
|
|
/* L100: */
|
|
}
|
|
} else {
|
|
jx = kx;
|
|
jy = ky;
|
|
i__1 = *n;
|
|
for (j = 1; j <= i__1; ++j) {
|
|
temp1 = *alpha * x[jx];
|
|
temp2 = 0.;
|
|
y[jy] += temp1 * a_ref(j, j);
|
|
ix = jx;
|
|
iy = jy;
|
|
i__2 = *n;
|
|
for (i__ = j + 1; i__ <= i__2; ++i__) {
|
|
ix += *incx;
|
|
iy += *incy;
|
|
y[iy] += temp1 * a_ref(i__, j);
|
|
temp2 += a_ref(i__, j) * x[ix];
|
|
/* L110: */
|
|
}
|
|
y[jy] += *alpha * temp2;
|
|
jx += *incx;
|
|
jy += *incy;
|
|
/* L120: */
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
/* End of DSYMV . */
|
|
} /* dsymv_ */
|
|
#undef a_ref
|
|
|
|
#ifdef _cpluscplus
|
|
}
|
|
#endif
|