242 lines
7.2 KiB
C
242 lines
7.2 KiB
C
/* dtrcon.f -- translated by f2c (version 20031025).
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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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cc *.o -lf2c -lm
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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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*/
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#include "f2c.h"
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/* Table of constant values */
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static integer c__1 = 1;
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/* Subroutine */ int dtrcon_(char *norm, char *uplo, char *diag, integer *n,
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doublereal *a, integer *lda, doublereal *rcond, doublereal *work,
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integer *iwork, integer *info, ftnlen norm_len, ftnlen uplo_len,
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ftnlen diag_len)
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{
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/* System generated locals */
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integer a_dim1, a_offset, i__1;
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doublereal d__1;
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/* Local variables */
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static integer ix, kase, kase1;
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static doublereal scale;
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extern logical lsame_(char *, char *, ftnlen, ftnlen);
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extern /* Subroutine */ int drscl_(integer *, doublereal *, doublereal *,
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integer *);
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static doublereal anorm;
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static logical upper;
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static doublereal xnorm;
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extern doublereal dlamch_(char *, ftnlen);
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extern /* Subroutine */ int dlacon_(integer *, doublereal *, doublereal *,
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integer *, doublereal *, integer *);
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extern integer idamax_(integer *, doublereal *, integer *);
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extern /* Subroutine */ int xerbla_(char *, integer *, ftnlen);
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extern doublereal dlantr_(char *, char *, char *, integer *, integer *,
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doublereal *, integer *, doublereal *, ftnlen, ftnlen, ftnlen);
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static doublereal ainvnm;
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extern /* Subroutine */ int dlatrs_(char *, char *, char *, char *,
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integer *, doublereal *, integer *, doublereal *, doublereal *,
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doublereal *, integer *, ftnlen, ftnlen, ftnlen, ftnlen);
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static logical onenrm;
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static char normin[1];
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static doublereal smlnum;
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static logical nounit;
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/* -- LAPACK 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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/* March 31, 1993 */
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/* .. Scalar Arguments .. */
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/* .. */
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/* .. Array Arguments .. */
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/* .. */
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/* Purpose */
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/* ======= */
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/* DTRCON estimates the reciprocal of the condition number of a */
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/* triangular matrix A, in either the 1-norm or the infinity-norm. */
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/* The norm of A is computed and an estimate is obtained for */
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/* norm(inv(A)), then the reciprocal of the condition number is */
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/* computed as */
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/* RCOND = 1 / ( norm(A) * norm(inv(A)) ). */
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/* Arguments */
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/* ========= */
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/* NORM (input) CHARACTER*1 */
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/* Specifies whether the 1-norm condition number or the */
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/* infinity-norm condition number is required: */
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/* = '1' or 'O': 1-norm; */
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/* = 'I': Infinity-norm. */
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/* UPLO (input) CHARACTER*1 */
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/* = 'U': A is upper triangular; */
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/* = 'L': A is lower triangular. */
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/* DIAG (input) CHARACTER*1 */
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/* = 'N': A is non-unit triangular; */
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/* = 'U': A is unit triangular. */
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/* N (input) INTEGER */
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/* The order of the matrix A. N >= 0. */
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/* A (input) DOUBLE PRECISION array, dimension (LDA,N) */
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/* The triangular matrix A. If UPLO = 'U', the leading N-by-N */
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/* upper triangular part of the array A contains the upper */
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/* triangular matrix, and the strictly lower triangular part of */
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/* A is not referenced. If UPLO = 'L', the leading N-by-N lower */
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/* triangular part of the array A contains the lower triangular */
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/* matrix, and the strictly upper triangular part of A is not */
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/* referenced. If DIAG = 'U', the diagonal elements of A are */
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/* also not referenced and are assumed to be 1. */
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/* LDA (input) INTEGER */
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/* The leading dimension of the array A. LDA >= max(1,N). */
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/* RCOND (output) DOUBLE PRECISION */
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/* The reciprocal of the condition number of the matrix A, */
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/* computed as RCOND = 1/(norm(A) * norm(inv(A))). */
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/* WORK (workspace) DOUBLE PRECISION array, dimension (3*N) */
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/* IWORK (workspace) INTEGER array, dimension (N) */
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/* INFO (output) INTEGER */
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/* = 0: successful exit */
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/* < 0: if INFO = -i, the i-th argument had an illegal value */
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/* ===================================================================== */
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/* .. Parameters .. */
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/* .. */
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/* .. Local Scalars .. */
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/* .. */
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/* .. External Functions .. */
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/* .. */
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/* .. External Subroutines .. */
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/* .. */
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/* .. Intrinsic Functions .. */
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/* .. */
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/* .. Executable Statements .. */
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/* Test the input parameters. */
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/* Parameter adjustments */
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a_dim1 = *lda;
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a_offset = 1 + a_dim1;
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a -= a_offset;
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--work;
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--iwork;
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/* Function Body */
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*info = 0;
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upper = lsame_(uplo, "U", (ftnlen)1, (ftnlen)1);
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onenrm = *(unsigned char *)norm == '1' || lsame_(norm, "O", (ftnlen)1, (
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ftnlen)1);
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nounit = lsame_(diag, "N", (ftnlen)1, (ftnlen)1);
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if (! onenrm && ! lsame_(norm, "I", (ftnlen)1, (ftnlen)1)) {
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*info = -1;
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} else if (! upper && ! lsame_(uplo, "L", (ftnlen)1, (ftnlen)1)) {
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*info = -2;
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} else if (! nounit && ! lsame_(diag, "U", (ftnlen)1, (ftnlen)1)) {
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*info = -3;
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} else if (*n < 0) {
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*info = -4;
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} else if (*lda < max(1,*n)) {
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*info = -6;
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}
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if (*info != 0) {
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i__1 = -(*info);
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xerbla_("DTRCON", &i__1, (ftnlen)6);
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return 0;
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}
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/* Quick return if possible */
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if (*n == 0) {
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*rcond = 1.;
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return 0;
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}
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*rcond = 0.;
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smlnum = dlamch_("Safe minimum", (ftnlen)12) * (doublereal) max(1,*n);
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/* Compute the norm of the triangular matrix A. */
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anorm = dlantr_(norm, uplo, diag, n, n, &a[a_offset], lda, &work[1], (
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ftnlen)1, (ftnlen)1, (ftnlen)1);
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/* Continue only if ANORM > 0. */
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if (anorm > 0.) {
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/* Estimate the norm of the inverse of A. */
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ainvnm = 0.;
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*(unsigned char *)normin = 'N';
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if (onenrm) {
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kase1 = 1;
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} else {
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kase1 = 2;
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}
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kase = 0;
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L10:
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dlacon_(n, &work[*n + 1], &work[1], &iwork[1], &ainvnm, &kase);
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if (kase != 0) {
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if (kase == kase1) {
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/* Multiply by inv(A). */
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dlatrs_(uplo, "No transpose", diag, normin, n, &a[a_offset],
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lda, &work[1], &scale, &work[(*n << 1) + 1], info, (
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ftnlen)1, (ftnlen)12, (ftnlen)1, (ftnlen)1);
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} else {
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/* Multiply by inv(A'). */
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dlatrs_(uplo, "Transpose", diag, normin, n, &a[a_offset], lda,
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&work[1], &scale, &work[(*n << 1) + 1], info, (
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ftnlen)1, (ftnlen)9, (ftnlen)1, (ftnlen)1);
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}
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*(unsigned char *)normin = 'Y';
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/* Multiply by 1/SCALE if doing so will not cause overflow. */
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if (scale != 1.) {
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ix = idamax_(n, &work[1], &c__1);
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xnorm = (d__1 = work[ix], abs(d__1));
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if (scale < xnorm * smlnum || scale == 0.) {
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goto L20;
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}
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drscl_(n, &scale, &work[1], &c__1);
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}
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goto L10;
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}
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/* Compute the estimate of the reciprocal condition number. */
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if (ainvnm != 0.) {
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*rcond = 1. / anorm / ainvnm;
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}
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}
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L20:
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return 0;
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/* End of DTRCON */
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} /* dtrcon_ */
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