Function drot_

numpy/linalg/lapack_lite/f2c_blas.c:7743–7816

Subroutine */

} /* dnrm2_ */

/* Subroutine */ int drot_(integer *n, doublereal *dx, integer *incx,
	doublereal *dy, integer *incy, doublereal *c__, doublereal *s)
{
    /* System generated locals */
    integer i__1;

    /* Local variables */
    static integer i__, ix, iy;
    static doublereal dtemp;


/*
    Purpose
    =======

       DROT applies a plane rotation.

    Further Details
    ===============

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

    =====================================================================
*/

    /* Parameter adjustments */
    --dy;
    --dx;

    /* 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__) {
	dtemp = *c__ * dx[ix] + *s * dy[iy];
	dy[iy] = *c__ * dy[iy] - *s * dx[ix];
	dx[ix] = dtemp;
	ix += *incx;
	iy += *incy;