annotate ext/cblas/src/dscal.c @ 464:0076c66d2932

Credit daschuer

/* dscal.f -- translated by f2c (version 20061008).
   You must link the resulting object file with libf2c:
	on Microsoft Windows system, link with libf2c.lib;
	on Linux or Unix systems, link with .../path/to/libf2c.a -lm
	or, if you install libf2c.a in a standard place, with -lf2c -lm
	-- in that order, at the end of the command line, as in
		cc *.o -lf2c -lm
	Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,

		http://www.netlib.org/f2c/libf2c.zip
*/

#include "f2c.h"
#include "blaswrap.h"

/* Subroutine */ int dscal_(integer *n, doublereal *da, doublereal *dx, 
	integer *incx)
{
    /* System generated locals */
    integer i__1, i__2;

    /* Local variables */
    integer i__, m, mp1, nincx;

/*     .. Scalar Arguments .. */
/*     .. */
/*     .. Array Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */
/* * */
/*     scales a vector by a constant. */
/*     uses unrolled loops for increment equal to one. */
/*     jack dongarra, linpack, 3/11/78. */
/*     modified 3/93 to return if incx .le. 0. */
/*     modified 12/3/93, array(1) declarations changed to array(*) */


/*     .. Local Scalars .. */
/*     .. */
/*     .. Intrinsic Functions .. */
/*     .. */
    /* Parameter adjustments */
    --dx;

    /* Function Body */
    if (*n <= 0 || *incx <= 0) {
	return 0;
    }
    if (*incx == 1) {
	goto L20;
    }

/*        code for increment not equal to 1 */

    nincx = *n * *incx;
    i__1 = nincx;
    i__2 = *incx;
    for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) {
	dx[i__] = *da * dx[i__];
/* L10: */
    }
    return 0;

/*        code for increment equal to 1 */


/*        clean-up loop */

L20:
    m = *n % 5;
    if (m == 0) {
	goto L40;
    }
    i__2 = m;
    for (i__ = 1; i__ <= i__2; ++i__) {
	dx[i__] = *da * dx[i__];
/* L30: */
    }
    if (*n < 5) {
	return 0;
    }
L40:
    mp1 = m + 1;
    i__2 = *n;
    for (i__ = mp1; i__ <= i__2; i__ += 5) {
	dx[i__] = *da * dx[i__];
	dx[i__ + 1] = *da * dx[i__ + 1];
	dx[i__ + 2] = *da * dx[i__ + 2];
	dx[i__ + 3] = *da * dx[i__ + 3];
	dx[i__ + 4] = *da * dx[i__ + 4];
/* L50: */
    }
    return 0;
} /* dscal_ */