#include "f2c.h"
/* Subroutine */ int zsymv_(char *uplo, integer *n, doublecomplex *alpha,
doublecomplex *a, integer *lda, doublecomplex *x, integer *incx,
doublecomplex *beta, doublecomplex *y, integer *incy)
{
/* -- LAPACK auxiliary routine (version 2.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
October 31, 1992
Purpose
=======
ZSYMV 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.
Arguments
==========
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 - COMPLEX*16
On entry, ALPHA specifies the scalar alpha.
Unchanged on exit.
A - COMPLEX*16 array, 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 - COMPLEX*16 array, 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 - COMPLEX*16
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 - COMPLEX*16 array, 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.
=====================================================================
Test the input parameters.
Parameter adjustments
Function Body */
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3, i__4, i__5;
doublecomplex z__1, z__2, z__3, z__4;
/* Local variables */
static integer info;
static doublecomplex 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 X(I) x[(I)-1]
#define Y(I) y[(I)-1]
#define A(I,J) a[(I)-1 + ((J)-1)* ( *lda)]
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_("ZSYMV ", &info);
return 0;
}
/* Quick return if possible. */
if (*n == 0 || alpha->r == 0. && alpha->i == 0. && (beta->r == 1. &&
beta->i == 0.)) {
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->r != 1. || beta->i != 0.) {
if (*incy == 1) {
if (beta->r == 0. && beta->i == 0.) {
i__1 = *n;
for (i = 1; i <= *n; ++i) {
i__2 = i;
Y(i).r = 0., Y(i).i = 0.;
/* L10: */
}
} else {
i__1 = *n;
for (i = 1; i <= *n; ++i) {
i__2 = i;
i__3 = i;
z__1.r = beta->r * Y(i).r - beta->i * Y(i).i,
z__1.i = beta->r * Y(i).i + beta->i * Y(i)
.r;
Y(i).r = z__1.r, Y(i).i = z__1.i;
/* L20: */
}
}
} else {
iy = ky;
if (beta->r == 0. && beta->i == 0.) {
i__1 = *n;
for (i = 1; i <= *n; ++i) {
i__2 = iy;
Y(iy).r = 0., Y(iy).i = 0.;
iy += *incy;
/* L30: */
}
} else {
i__1 = *n;
for (i = 1; i <= *n; ++i) {
i__2 = iy;
i__3 = iy;
z__1.r = beta->r * Y(iy).r - beta->i * Y(iy).i,
z__1.i = beta->r * Y(iy).i + beta->i * Y(iy)
.r;
Y(iy).r = z__1.r, Y(iy).i = z__1.i;
iy += *incy;
/* L40: */
}
}
}
}
if (alpha->r == 0. && alpha->i == 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 <= *n; ++j) {
i__2 = j;
z__1.r = alpha->r * X(j).r - alpha->i * X(j).i, z__1.i =
alpha->r * X(j).i + alpha->i * X(j).r;
temp1.r = z__1.r, temp1.i = z__1.i;
temp2.r = 0., temp2.i = 0.;
i__2 = j - 1;
for (i = 1; i <= j-1; ++i) {
i__3 = i;
i__4 = i;
i__5 = i + j * a_dim1;
z__2.r = temp1.r * A(i,j).r - temp1.i * A(i,j).i,
z__2.i = temp1.r * A(i,j).i + temp1.i * A(i,j)
.r;
z__1.r = Y(i).r + z__2.r, z__1.i = Y(i).i + z__2.i;
Y(i).r = z__1.r, Y(i).i = z__1.i;
i__3 = i + j * a_dim1;
i__4 = i;
z__2.r = A(i,j).r * X(i).r - A(i,j).i * X(i).i,
z__2.i = A(i,j).r * X(i).i + A(i,j).i * X(
i).r;
z__1.r = temp2.r + z__2.r, z__1.i = temp2.i + z__2.i;
temp2.r = z__1.r, temp2.i = z__1.i;
/* L50: */
}
i__2 = j;
i__3 = j;
i__4 = j + j * a_dim1;
z__3.r = temp1.r * A(j,j).r - temp1.i * A(j,j).i, z__3.i =
temp1.r * A(j,j).i + temp1.i * A(j,j).r;
z__2.r = Y(j).r + z__3.r, z__2.i = Y(j).i + z__3.i;
z__4.r = alpha->r * temp2.r - alpha->i * temp2.i, z__4.i =
alpha->r * temp2.i + alpha->i * temp2.r;
z__1.r = z__2.r + z__4.r, z__1.i = z__2.i + z__4.i;
Y(j).r = z__1.r, Y(j).i = z__1.i;
/* L60: */
}
} else {
jx = kx;
jy = ky;
i__1 = *n;
for (j = 1; j <= *n; ++j) {
i__2 = jx;
z__1.r = alpha->r * X(jx).r - alpha->i * X(jx).i, z__1.i =
alpha->r * X(jx).i + alpha->i * X(jx).r;
temp1.r = z__1.r, temp1.i = z__1.i;
temp2.r = 0., temp2.i = 0.;
ix = kx;
iy = ky;
i__2 = j - 1;
for (i = 1; i <= j-1; ++i) {
i__3 = iy;
i__4 = iy;
i__5 = i + j * a_dim1;
z__2.r = temp1.r * A(i,j).r - temp1.i * A(i,j).i,
z__2.i = temp1.r * A(i,j).i + temp1.i * A(i,j)
.r;
z__1.r = Y(iy).r + z__2.r, z__1.i = Y(iy).i + z__2.i;
Y(iy).r = z__1.r, Y(iy).i = z__1.i;
i__3 = i + j * a_dim1;
i__4 = ix;
z__2.r = A(i,j).r * X(ix).r - A(i,j).i * X(ix).i,
z__2.i = A(i,j).r * X(ix).i + A(i,j).i * X(
ix).r;
z__1.r = temp2.r + z__2.r, z__1.i = temp2.i + z__2.i;
temp2.r = z__1.r, temp2.i = z__1.i;
ix += *incx;
iy += *incy;
/* L70: */
}
i__2 = jy;
i__3 = jy;
i__4 = j + j * a_dim1;
z__3.r = temp1.r * A(j,j).r - temp1.i * A(j,j).i, z__3.i =
temp1.r * A(j,j).i + temp1.i * A(j,j).r;
z__2.r = Y(jy).r + z__3.r, z__2.i = Y(jy).i + z__3.i;
z__4.r = alpha->r * temp2.r - alpha->i * temp2.i, z__4.i =
alpha->r * temp2.i + alpha->i * temp2.r;
z__1.r = z__2.r + z__4.r, z__1.i = z__2.i + z__4.i;
Y(jy).r = z__1.r, Y(jy).i = z__1.i;
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 <= *n; ++j) {
i__2 = j;
z__1.r = alpha->r * X(j).r - alpha->i * X(j).i, z__1.i =
alpha->r * X(j).i + alpha->i * X(j).r;
temp1.r = z__1.r, temp1.i = z__1.i;
temp2.r = 0., temp2.i = 0.;
i__2 = j;
i__3 = j;
i__4 = j + j * a_dim1;
z__2.r = temp1.r * A(j,j).r - temp1.i * A(j,j).i, z__2.i =
temp1.r * A(j,j).i + temp1.i * A(j,j).r;
z__1.r = Y(j).r + z__2.r, z__1.i = Y(j).i + z__2.i;
Y(j).r = z__1.r, Y(j).i = z__1.i;
i__2 = *n;
for (i = j + 1; i <= *n; ++i) {
i__3 = i;
i__4 = i;
i__5 = i + j * a_dim1;
z__2.r = temp1.r * A(i,j).r - temp1.i * A(i,j).i,
z__2.i = temp1.r * A(i,j).i + temp1.i * A(i,j)
.r;
z__1.r = Y(i).r + z__2.r, z__1.i = Y(i).i + z__2.i;
Y(i).r = z__1.r, Y(i).i = z__1.i;
i__3 = i + j * a_dim1;
i__4 = i;
z__2.r = A(i,j).r * X(i).r - A(i,j).i * X(i).i,
z__2.i = A(i,j).r * X(i).i + A(i,j).i * X(
i).r;
z__1.r = temp2.r + z__2.r, z__1.i = temp2.i + z__2.i;
temp2.r = z__1.r, temp2.i = z__1.i;
/* L90: */
}
i__2 = j;
i__3 = j;
z__2.r = alpha->r * temp2.r - alpha->i * temp2.i, z__2.i =
alpha->r * temp2.i + alpha->i * temp2.r;
z__1.r = Y(j).r + z__2.r, z__1.i = Y(j).i + z__2.i;
Y(j).r = z__1.r, Y(j).i = z__1.i;
/* L100: */
}
} else {
jx = kx;
jy = ky;
i__1 = *n;
for (j = 1; j <= *n; ++j) {
i__2 = jx;
z__1.r = alpha->r * X(jx).r - alpha->i * X(jx).i, z__1.i =
alpha->r * X(jx).i + alpha->i * X(jx).r;
temp1.r = z__1.r, temp1.i = z__1.i;
temp2.r = 0., temp2.i = 0.;
i__2 = jy;
i__3 = jy;
i__4 = j + j * a_dim1;
z__2.r = temp1.r * A(j,j).r - temp1.i * A(j,j).i, z__2.i =
temp1.r * A(j,j).i + temp1.i * A(j,j).r;
z__1.r = Y(jy).r + z__2.r, z__1.i = Y(jy).i + z__2.i;
Y(jy).r = z__1.r, Y(jy).i = z__1.i;
ix = jx;
iy = jy;
i__2 = *n;
for (i = j + 1; i <= *n; ++i) {
ix += *incx;
iy += *incy;
i__3 = iy;
i__4 = iy;
i__5 = i + j * a_dim1;
z__2.r = temp1.r * A(i,j).r - temp1.i * A(i,j).i,
z__2.i = temp1.r * A(i,j).i + temp1.i * A(i,j)
.r;
z__1.r = Y(iy).r + z__2.r, z__1.i = Y(iy).i + z__2.i;
Y(iy).r = z__1.r, Y(iy).i = z__1.i;
i__3 = i + j * a_dim1;
i__4 = ix;
z__2.r = A(i,j).r * X(ix).r - A(i,j).i * X(ix).i,
z__2.i = A(i,j).r * X(ix).i + A(i,j).i * X(
ix).r;
z__1.r = temp2.r + z__2.r, z__1.i = temp2.i + z__2.i;
temp2.r = z__1.r, temp2.i = z__1.i;
/* L110: */
}
i__2 = jy;
i__3 = jy;
z__2.r = alpha->r * temp2.r - alpha->i * temp2.i, z__2.i =
alpha->r * temp2.i + alpha->i * temp2.r;
z__1.r = Y(jy).r + z__2.r, z__1.i = Y(jy).i + z__2.i;
Y(jy).r = z__1.r, Y(jy).i = z__1.i;
jx += *incx;
jy += *incy;
/* L120: */
}
}
}
return 0;
/* End of ZSYMV */
} /* zsymv_ */