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#include "clapack.h"
/* Subroutine */ int sger_(integer *_m, integer *_n, real *_alpha,
real *x, integer *_incx, real *y, integer *_incy,
real *a, integer *_lda)
{
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* SGER performs the rank 1 operation */
/* A := alpha*x*y' + A, */
/* where alpha is a scalar, x is an m element vector, y is an n element */
/* vector and A is an m by n matrix. */
/* Arguments */
/* ========== */
/* M - INTEGER. */
/* On entry, M specifies the number of rows of the matrix A. */
/* M must be at least zero. */
/* Unchanged on exit. */
/* N - INTEGER. */
/* On entry, N specifies the number of columns of the matrix A. */
/* N must be at least zero. */
/* Unchanged on exit. */
/* ALPHA - SINGLE PRECISION. */
/* On entry, ALPHA specifies the scalar alpha. */
/* Unchanged on exit. */
/* X - SINGLE PRECISION array of dimension at least */
/* ( 1 + ( m - 1 )*abs( INCX ) ). */
/* Before entry, the incremented array X must contain the m */
/* 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 - SINGLE PRECISION 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 - SINGLE PRECISION array of DIMENSION ( LDA, n ). */
/* Before entry, the leading m by n part of the array A must */
/* contain the matrix of coefficients. On exit, A is */
/* overwritten by 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, m ). */
/* 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 Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* Test the input parameters. */
/* Function Body */
integer i, j, m = *_m, n = *_n, incx = *_incx, incy = *_incy, lda = *_lda;
real alpha = *_alpha;
integer info = 0;
if (m < 0)
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,m))
info = 9;
if (info != 0)
{
xerbla_("SGER ", &info);
return 0;
}
if (incx < 0)
x -= (m-1)*incx;
if (incy < 0)
y -= (n-1)*incy;
/* Start the operations. In this version the elements of A are */
/* accessed sequentially with one pass through A. */
if( alpha == 0 )
;
else if( incx == 1 )
{
for( j = 0; j < n; j++, a += lda )
{
real s = y[j*incy];
if( s == 0 )
continue;
s *= alpha;
for( i = 0; i <= m - 2; i += 2 )
{
real t0 = a[i] + x[i]*s;
real t1 = a[i+1] + x[i+1]*s;
a[i] = t0; a[i+1] = t1;
}
for( ; i < m; i++ )
a[i] += x[i]*s;
}
}
else
{
for( j = 0; j < n; j++, a += lda )
{
real s = y[j*incy];
if( s == 0 )
continue;
s *= alpha;
for( i = 0; i < m; i++ )
a[i] += x[i*incx]*s;
}
}
return 0;
/* End of SGER . */
} /* sger_ */