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drotm.c
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Tue, Feb 11, 16:53

drotm.c
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/* drotm.f -- translated by f2c (version 20100827).
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 "datatypes.h"
/* Subroutine */ int drotm_(integer *n, doublereal *dx, integer *incx,
doublereal *dy, integer *incy, doublereal *dparam)
{
/* Initialized data */
static doublereal zero = 0.;
static doublereal two = 2.;
/* System generated locals */
integer i__1, i__2;
/* Local variables */
integer i__;
doublereal w, z__;
integer kx, ky;
doublereal dh11, dh12, dh21, dh22, dflag;
integer nsteps;
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX */
/* (DX**T) , WHERE **T INDICATES TRANSPOSE. THE ELEMENTS OF DX ARE IN */
/* (DY**T) */
/* DX(LX+I*INCX), I = 0 TO N-1, WHERE LX = 1 IF INCX .GE. 0, ELSE */
/* LX = (-INCX)*N, AND SIMILARLY FOR SY USING LY AND INCY. */
/* WITH DPARAM(1)=DFLAG, H HAS ONE OF THE FOLLOWING FORMS.. */
/* DFLAG=-1.D0 DFLAG=0.D0 DFLAG=1.D0 DFLAG=-2.D0 */
/* (DH11 DH12) (1.D0 DH12) (DH11 1.D0) (1.D0 0.D0) */
/* H=( ) ( ) ( ) ( ) */
/* (DH21 DH22), (DH21 1.D0), (-1.D0 DH22), (0.D0 1.D0). */
/* SEE DROTMG FOR A DESCRIPTION OF DATA STORAGE IN DPARAM. */
/* Arguments */
/* ========= */
/* N (input) INTEGER */
/* number of elements in input vector(s) */
/* DX (input/output) DOUBLE PRECISION array, dimension N */
/* double precision vector with N elements */
/* INCX (input) INTEGER */
/* storage spacing between elements of DX */
/* DY (input/output) DOUBLE PRECISION array, dimension N */
/* double precision vector with N elements */
/* INCY (input) INTEGER */
/* storage spacing between elements of DY */
/* DPARAM (input/output) DOUBLE PRECISION array, dimension 5 */
/* DPARAM(1)=DFLAG */
/* DPARAM(2)=DH11 */
/* DPARAM(3)=DH21 */
/* DPARAM(4)=DH12 */
/* DPARAM(5)=DH22 */
/* ===================================================================== */
/* .. Local Scalars .. */
/* .. */
/* .. Data statements .. */
/* Parameter adjustments */
--dparam;
--dy;
--dx;
/* Function Body */
/* .. */
dflag = dparam[1];
if (*n <= 0 || dflag + two == zero) {
goto L140;
}
if (! (*incx == *incy && *incx > 0)) {
goto L70;
}
nsteps = *n * *incx;
if (dflag < 0.) {
goto L50;
} else if (dflag == 0) {
goto L10;
} else {
goto L30;
}
L10:
dh12 = dparam[4];
dh21 = dparam[3];
i__1 = nsteps;
i__2 = *incx;
for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) {
w = dx[i__];
z__ = dy[i__];
dx[i__] = w + z__ * dh12;
dy[i__] = w * dh21 + z__;
/* L20: */
}
goto L140;
L30:
dh11 = dparam[2];
dh22 = dparam[5];
i__2 = nsteps;
i__1 = *incx;
for (i__ = 1; i__1 < 0 ? i__ >= i__2 : i__ <= i__2; i__ += i__1) {
w = dx[i__];
z__ = dy[i__];
dx[i__] = w * dh11 + z__;
dy[i__] = -w + dh22 * z__;
/* L40: */
}
goto L140;
L50:
dh11 = dparam[2];
dh12 = dparam[4];
dh21 = dparam[3];
dh22 = dparam[5];
i__1 = nsteps;
i__2 = *incx;
for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) {
w = dx[i__];
z__ = dy[i__];
dx[i__] = w * dh11 + z__ * dh12;
dy[i__] = w * dh21 + z__ * dh22;
/* L60: */
}
goto L140;
L70:
kx = 1;
ky = 1;
if (*incx < 0) {
kx = (1 - *n) * *incx + 1;
}
if (*incy < 0) {
ky = (1 - *n) * *incy + 1;
}
if (dflag < 0.) {
goto L120;
} else if (dflag == 0) {
goto L80;
} else {
goto L100;
}
L80:
dh12 = dparam[4];
dh21 = dparam[3];
i__2 = *n;
for (i__ = 1; i__ <= i__2; ++i__) {
w = dx[kx];
z__ = dy[ky];
dx[kx] = w + z__ * dh12;
dy[ky] = w * dh21 + z__;
kx += *incx;
ky += *incy;
/* L90: */
}
goto L140;
L100:
dh11 = dparam[2];
dh22 = dparam[5];
i__2 = *n;
for (i__ = 1; i__ <= i__2; ++i__) {
w = dx[kx];
z__ = dy[ky];
dx[kx] = w * dh11 + z__;
dy[ky] = -w + dh22 * z__;
kx += *incx;
ky += *incy;
/* L110: */
}
goto L140;
L120:
dh11 = dparam[2];
dh12 = dparam[4];
dh21 = dparam[3];
dh22 = dparam[5];
i__2 = *n;
for (i__ = 1; i__ <= i__2; ++i__) {
w = dx[kx];
z__ = dy[ky];
dx[kx] = w * dh11 + z__ * dh12;
dy[ky] = w * dh21 + z__ * dh22;
kx += *incx;
ky += *incy;
/* L130: */
}
L140:
return 0;
} /* drotm_ */

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