/* drotmg.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 drotmg_(doublereal *dd1, doublereal *dd2, doublereal *
dx1, doublereal *dy1, doublereal *dparam)
{
/* Initialized data */
static doublereal zero = 0.;
static doublereal one = 1.;
static doublereal two = 2.;
static doublereal gam = 4096.;
static doublereal gamsq = 16777216.;
static doublereal rgamsq = 5.9604645e-8;
/* Format strings */
static char fmt_120[] = "";
static char fmt_150[] = "";
static char fmt_180[] = "";
static char fmt_210[] = "";
/* System generated locals */
doublereal d__1;
/* Local variables */
doublereal du, dp1, dp2, dq1, dq2, dh11, dh12, dh21, dh22;
integer igo;
doublereal dflag, dtemp;
/* Assigned format variables */
static char *igo_fmt;
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* CONSTRUCT THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH ZEROS */
/* THE SECOND COMPONENT OF THE 2-VECTOR (DSQRT(DD1)*DX1,DSQRT(DD2)* */
/* DY2)**T. */
/* 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). */
/* LOCATIONS 2-4 OF DPARAM CONTAIN DH11, DH21, DH12, AND DH22 */
/* RESPECTIVELY. (VALUES OF 1.D0, -1.D0, OR 0.D0 IMPLIED BY THE */
/* VALUE OF DPARAM(1) ARE NOT STORED IN DPARAM.) */
/* THE VALUES OF GAMSQ AND RGAMSQ SET IN THE DATA STATEMENT MAY BE */
/* INEXACT. THIS IS OK AS THEY ARE ONLY USED FOR TESTING THE SIZE */
/* OF DD1 AND DD2. ALL ACTUAL SCALING OF DATA IS DONE USING GAM. */
/* Arguments */
/* ========= */
/* DD1 (input/output) DOUBLE PRECISION */
/* DD2 (input/output) DOUBLE PRECISION */
/* DX1 (input/output) DOUBLE PRECISION */
/* DY1 (input) DOUBLE PRECISION */
/* 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 .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Data statements .. */
/* Parameter adjustments */
--dparam;
/* Function Body */
/* .. */
if (! (*dd1 < zero)) {
goto L10;
}
/* GO ZERO-H-D-AND-DX1.. */
goto L60;
L10:
/* CASE-DD1-NONNEGATIVE */
dp2 = *dd2 * *dy1;
if (! (dp2 == zero)) {
goto L20;
}
dflag = -two;
goto L260;
/* REGULAR-CASE.. */
L20:
dp1 = *dd1 * *dx1;
dq2 = dp2 * *dy1;
dq1 = dp1 * *dx1;
if (! (abs(dq1) > abs(dq2))) {
goto L40;
}
dh21 = -(*dy1) / *dx1;
dh12 = dp2 / dp1;
du = one - dh12 * dh21;
if (! (du <= zero)) {
goto L30;
}
/* GO ZERO-H-D-AND-DX1.. */
goto L60;
L30:
dflag = zero;
*dd1 /= du;
*dd2 /= du;
*dx1 *= du;
/* GO SCALE-CHECK.. */
goto L100;
L40:
if (! (dq2 < zero)) {
goto L50;
}
/* GO ZERO-H-D-AND-DX1.. */
goto L60;
L50:
dflag = one;
dh11 = dp1 / dp2;
dh22 = *dx1 / *dy1;
du = one + dh11 * dh22;
dtemp = *dd2 / du;
*dd2 = *dd1 / du;
*dd1 = dtemp;
*dx1 = *dy1 * du;
/* GO SCALE-CHECK */
goto L100;
/* PROCEDURE..ZERO-H-D-AND-DX1.. */
L60:
dflag = -one;
dh11 = zero;
dh12 = zero;
dh21 = zero;
dh22 = zero;
*dd1 = zero;
*dd2 = zero;
*dx1 = zero;
/* RETURN.. */
goto L220;
/* PROCEDURE..FIX-H.. */
L70:
if (! (dflag >= zero)) {
goto L90;
}
if (! (dflag == zero)) {
goto L80;
}
dh11 = one;
dh22 = one;
dflag = -one;
goto L90;
L80:
dh21 = -one;
dh12 = one;
dflag = -one;
L90:
switch (igo) {
case 0: goto L120;
case 1: goto L150;
case 2: goto L180;
case 3: goto L210;
}
/* PROCEDURE..SCALE-CHECK */
L100:
L110:
if (! (*dd1 <= rgamsq)) {
goto L130;
}
if (*dd1 == zero) {
goto L160;
}
igo = 0;
igo_fmt = fmt_120;
/* FIX-H.. */
goto L70;
L120:
/* Computing 2nd power */
d__1 = gam;
*dd1 *= d__1 * d__1;
*dx1 /= gam;
dh11 /= gam;
dh12 /= gam;
goto L110;
L130:
L140:
if (! (*dd1 >= gamsq)) {
goto L160;
}
igo = 1;
igo_fmt = fmt_150;
/* FIX-H.. */
goto L70;
L150:
/* Computing 2nd power */
d__1 = gam;
*dd1 /= d__1 * d__1;
*dx1 *= gam;
dh11 *= gam;
dh12 *= gam;
goto L140;
L160:
L170:
if (! (abs(*dd2) <= rgamsq)) {
goto L190;
}
if (*dd2 == zero) {
goto L220;
}
igo = 2;
igo_fmt = fmt_180;
/* FIX-H.. */
goto L70;
L180:
/* Computing 2nd power */
d__1 = gam;
*dd2 *= d__1 * d__1;
dh21 /= gam;
dh22 /= gam;
goto L170;
L190:
L200:
if (! (abs(*dd2) >= gamsq)) {
goto L220;
}
igo = 3;
igo_fmt = fmt_210;
/* FIX-H.. */
goto L70;
L210:
/* Computing 2nd power */
d__1 = gam;
*dd2 /= d__1 * d__1;
dh21 *= gam;
dh22 *= gam;
goto L200;
L220:
if (dflag < 0.) {
goto L250;
} else if (dflag == 0) {
goto L230;
} else {
goto L240;
}
L230:
dparam[3] = dh21;
dparam[4] = dh12;
goto L260;
L240:
dparam[2] = dh11;
dparam[5] = dh22;
goto L260;
L250:
dparam[2] = dh11;
dparam[3] = dh21;
dparam[4] = dh12;
dparam[5] = dh22;
L260:
dparam[1] = dflag;
return 0;
} /* drotmg_ */