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/* -- translated by f2c (version 20050501).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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#include "arpack_internal.h"
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/* Subroutine */ int igraphdlartg_(doublereal *f, doublereal *g, doublereal *cs,
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doublereal *sn, doublereal *r__)
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/* Initialized data */
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static logical first = TRUE_;
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/* System generated locals */
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doublereal d__1, d__2;
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/* Builtin functions */
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double log(doublereal), igraphpow_di(doublereal *, integer *), sqrt(doublereal);
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static doublereal f1, g1, eps, scale;
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static doublereal safmn2, safmx2;
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extern doublereal igraphdlamch_(char *);
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static doublereal safmin;
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/* -- LAPACK auxiliary routine (version 3.0) -- */
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/* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
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/* Courant Institute, Argonne National Lab, and Rice University */
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/* September 30, 1994 */
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/* .. Scalar Arguments .. */
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/* DLARTG generate a plane rotation so that */
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/* [ CS SN ] . [ F ] = [ R ] where CS**2 + SN**2 = 1. */
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/* [ -SN CS ] [ G ] [ 0 ] */
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/* This is a slower, more accurate version of the BLAS1 routine DROTG, */
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/* with the following other differences: */
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/* F and G are unchanged on return. */
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/* If G=0, then CS=1 and SN=0. */
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/* If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any */
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/* floating point operations (saves work in DBDSQR when */
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/* there are zeros on the diagonal). */
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/* If F exceeds G in magnitude, CS will be positive. */
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/* F (input) DOUBLE PRECISION */
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/* The first component of vector to be rotated. */
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/* G (input) DOUBLE PRECISION */
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/* The second component of vector to be rotated. */
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/* CS (output) DOUBLE PRECISION */
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/* The cosine of the rotation. */
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/* SN (output) DOUBLE PRECISION */
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/* The sine of the rotation. */
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/* R (output) DOUBLE PRECISION */
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/* The nonzero component of the rotated vector. */
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/* ===================================================================== */
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/* .. Parameters .. */
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/* .. Local Scalars .. */
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/* .. External Functions .. */
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/* .. Intrinsic Functions .. */
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/* .. Save statement .. */
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/* .. Data statements .. */
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/* .. Executable Statements .. */
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safmin = igraphdlamch_("S");
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eps = igraphdlamch_("E");
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d__1 = igraphdlamch_("B");
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i__1 = (integer) (log(safmin / eps) / log(igraphdlamch_("B")) /
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safmn2 = igraphpow_di(&d__1, &i__1);
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safmx2 = 1. / safmn2;
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} else if (*f == 0.) {
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d__1 = abs(f1), d__2 = abs(g1);
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scale = max(d__1,d__2);
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if (scale >= safmx2) {
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d__1 = abs(f1), d__2 = abs(g1);
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scale = max(d__1,d__2);
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if (scale >= safmx2) {
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/* Computing 2nd power */
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/* Computing 2nd power */
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*r__ = sqrt(d__1 * d__1 + d__2 * d__2);
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for (i__ = 1; i__ <= i__1; ++i__) {
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} else if (scale <= safmn2) {
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d__1 = abs(f1), d__2 = abs(g1);
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scale = max(d__1,d__2);
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if (scale <= safmn2) {
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/* Computing 2nd power */
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/* Computing 2nd power */
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*r__ = sqrt(d__1 * d__1 + d__2 * d__2);
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for (i__ = 1; i__ <= i__1; ++i__) {
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/* Computing 2nd power */
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/* Computing 2nd power */
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*r__ = sqrt(d__1 * d__1 + d__2 * d__2);
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if (abs(*f) > abs(*g) && *cs < 0.) {
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} /* igraphdlartg_ */
added
removed
src/lapack/dlartg.c
