srot.c

/* srot.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 "clapack.h"


/* Subroutine */ int srot_(integer *n, real *sx, integer *incx, real *sy, 
	integer *incy, real *c__, real *s)
{
    /* System generated locals */
    integer i__1;

    /* Local variables */
    integer i__, ix, iy;
    real stemp;

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

/*  Purpose */
/*  ======= */

/*     applies a plane rotation. */

/*  Further Details */
/*  =============== */

/*     jack dongarra, linpack, 3/11/78. */
/*     modified 12/3/93, array(1) declarations changed to array(*) */


/*     .. Local Scalars .. */
/*     .. */
    /* Parameter adjustments */
    --sy;
    --sx;

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

/*       code for unequal increments or equal increments not equal */
/*         to 1 */

    ix = 1;
    iy = 1;
    if (*incx < 0) {
	ix = (-(*n) + 1) * *incx + 1;
    }
    if (*incy < 0) {
	iy = (-(*n) + 1) * *incy + 1;
    }
    i__1 = *n;
    for (i__ = 1; i__ <= i__1; ++i__) {
	stemp = *c__ * sx[ix] + *s * sy[iy];
	sy[iy] = *c__ * sy[iy] - *s * sx[ix];
	sx[ix] = stemp;
	ix += *incx;
	iy += *incy;
/* L10: */
    }
    return 0;

/*       code for both increments equal to 1 */

L20:
    i__1 = *n;
    for (i__ = 1; i__ <= i__1; ++i__) {
	stemp = *c__ * sx[i__] + *s * sy[i__];
	sy[i__] = *c__ * sy[i__] - *s * sx[i__];
	sx[i__] = stemp;
/* L30: */
    }
    return 0;
} /* srot_ */