--- /dev/null
+#include "clapack.h"
+
+/* Subroutine */ int ssyr2_(char *uplo, integer *n, real *alpha, real *x,
+ integer *incx, real *y, integer *incy, real *a, integer *lda)
+{
+ /* System generated locals */
+ integer a_dim1, a_offset, i__1, i__2;
+
+ /* Local variables */
+ integer i__, j, ix, iy, jx, jy, kx, ky, info;
+ real temp1, temp2;
+ extern logical lsame_(char *, char *);
+ extern /* Subroutine */ int xerbla_(char *, integer *);
+
+/* .. Scalar Arguments .. */
+/* .. */
+/* .. Array Arguments .. */
+/* .. */
+
+/* Purpose */
+/* ======= */
+
+/* SSYR2 performs the symmetric rank 2 operation */
+
+/* A := alpha*x*y' + alpha*y*x' + A, */
+
+/* where alpha is a scalar, 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 - REAL . */
+/* On entry, ALPHA specifies the scalar alpha. */
+/* Unchanged on exit. */
+
+/* X - REAL 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. */
+
+/* Y - REAL array of dimension at least */
+/* ( 1 + ( n - 1 )*abs( INCY ) ). */
+/* Before entry, the incremented array Y must contain the n */
+/* element vector y. */
+/* Unchanged on exit. */
+
+/* INCY - INTEGER. */
+/* On entry, INCY specifies the increment for the elements of */
+/* Y. INCY must not be zero. */
+/* Unchanged on exit. */
+
+/* A - REAL 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. On exit, the */
+/* upper triangular part of the array A is overwritten by the */
+/* upper triangular part of the updated matrix. */
+/* 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. On exit, the */
+/* lower triangular part of the array A is overwritten by the */
+/* lower triangular part of the updated matrix. */
+
+/* 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. */
+
+
+/* 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. */
+
+
+/* .. Parameters .. */
+/* .. */
+/* .. Local Scalars .. */
+/* .. */
+/* .. External Functions .. */
+/* .. */
+/* .. External Subroutines .. */
+/* .. */
+/* .. Intrinsic Functions .. */
+/* .. */
+
+/* Test the input parameters. */
+
+ /* Parameter adjustments */
+ --x;
+ --y;
+ a_dim1 = *lda;
+ a_offset = 1 + a_dim1;
+ a -= a_offset;
+
+ /* Function Body */
+ info = 0;
+ if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) {
+ info = 1;
+ } else if (*n < 0) {
+ info = 2;
+ } else if (*incx == 0) {
+ info = 5;
+ } else if (*incy == 0) {
+ info = 7;
+ } else if (*lda < max(1,*n)) {
+ info = 9;
+ }
+ if (info != 0) {
+ xerbla_("SSYR2 ", &info);
+ return 0;
+ }
+
+/* Quick return if possible. */
+
+ if (*n == 0 || *alpha == 0.f) {
+ return 0;
+ }
+
+/* Set up the start points in X and Y if the increments are not both */
+/* unity. */
+
+ if (*incx != 1 || *incy != 1) {
+ if (*incx > 0) {
+ kx = 1;
+ } else {
+ kx = 1 - (*n - 1) * *incx;
+ }
+ if (*incy > 0) {
+ ky = 1;
+ } else {
+ ky = 1 - (*n - 1) * *incy;
+ }
+ jx = kx;
+ jy = ky;
+ }
+
+/* Start the operations. In this version the elements of A are */
+/* accessed sequentially with one pass through the triangular part */
+/* of A. */
+
+ if (lsame_(uplo, "U")) {
+
+/* Form A when A is stored in the upper triangle. */
+
+ if (*incx == 1 && *incy == 1) {
+ i__1 = *n;
+ for (j = 1; j <= i__1; ++j) {
+ if (x[j] != 0.f || y[j] != 0.f) {
+ temp1 = *alpha * y[j];
+ temp2 = *alpha * x[j];
+ i__2 = j;
+ for (i__ = 1; i__ <= i__2; ++i__) {
+ a[i__ + j * a_dim1] = a[i__ + j * a_dim1] + x[i__] *
+ temp1 + y[i__] * temp2;
+/* L10: */
+ }
+ }
+/* L20: */
+ }
+ } else {
+ i__1 = *n;
+ for (j = 1; j <= i__1; ++j) {
+ if (x[jx] != 0.f || y[jy] != 0.f) {
+ temp1 = *alpha * y[jy];
+ temp2 = *alpha * x[jx];
+ ix = kx;
+ iy = ky;
+ i__2 = j;
+ for (i__ = 1; i__ <= i__2; ++i__) {
+ a[i__ + j * a_dim1] = a[i__ + j * a_dim1] + x[ix] *
+ temp1 + y[iy] * temp2;
+ ix += *incx;
+ iy += *incy;
+/* L30: */
+ }
+ }
+ jx += *incx;
+ jy += *incy;
+/* L40: */
+ }
+ }
+ } else {
+
+/* Form A when A is stored in the lower triangle. */
+
+ if (*incx == 1 && *incy == 1) {
+ i__1 = *n;
+ for (j = 1; j <= i__1; ++j) {
+ if (x[j] != 0.f || y[j] != 0.f) {
+ temp1 = *alpha * y[j];
+ temp2 = *alpha * x[j];
+ i__2 = *n;
+ for (i__ = j; i__ <= i__2; ++i__) {
+ a[i__ + j * a_dim1] = a[i__ + j * a_dim1] + x[i__] *
+ temp1 + y[i__] * temp2;
+/* L50: */
+ }
+ }
+/* L60: */
+ }
+ } else {
+ i__1 = *n;
+ for (j = 1; j <= i__1; ++j) {
+ if (x[jx] != 0.f || y[jy] != 0.f) {
+ temp1 = *alpha * y[jy];
+ temp2 = *alpha * x[jx];
+ ix = jx;
+ iy = jy;
+ i__2 = *n;
+ for (i__ = j; i__ <= i__2; ++i__) {
+ a[i__ + j * a_dim1] = a[i__ + j * a_dim1] + x[ix] *
+ temp1 + y[iy] * temp2;
+ ix += *incx;
+ iy += *incy;
+/* L70: */
+ }
+ }
+ jx += *incx;
+ jy += *incy;
+/* L80: */
+ }
+ }
+ }
+
+ return 0;
+
+/* End of SSYR2 . */
+
+} /* ssyr2_ */
projects / opencv / blobdiff