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/* ../netlib/sgecon.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 "FLA_f2c.h" /* Table of constant values */
static integer c__1 = 1;
/* > \brief \b SGECON */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* > \htmlonly */
/* > Download SGECON + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/sgecon. f"> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/sgecon. f"> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/sgecon. f"> */
/* > [TXT]</a> */
/* > \endhtmlonly */
/* Definition: */
/* =========== */
/* SUBROUTINE SGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, */
/* INFO ) */
/* .. Scalar Arguments .. */
/* CHARACTER NORM */
/* INTEGER INFO, LDA, N */
/* REAL ANORM, RCOND */
/* .. */
/* .. Array Arguments .. */
/* INTEGER IWORK( * ) */
/* REAL A( LDA, * ), WORK( * ) */
/* .. */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > SGECON estimates the reciprocal of the condition number of a general */
/* > real matrix A, in either the 1-norm or the infinity-norm, using */
/* > the LU factorization computed by SGETRF. */
/* > */
/* > An estimate is obtained for norm(inv(A)), and the reciprocal of the */
/* > condition number is computed as */
/* > RCOND = 1 / ( norm(A) * norm(inv(A)) ). */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] NORM */
/* > \verbatim */
/* > NORM is CHARACTER*1 */
/* > Specifies whether the 1-norm condition number or the */
/* > infinity-norm condition number is required: */
/* > = '1' or 'O': 1-norm;
*/
/* > = 'I': Infinity-norm. */
/* > \endverbatim */
/* > */
/* > \param[in] N */
/* > \verbatim */
/* > N is INTEGER */
/* > The order of the matrix A. N >= 0. */
/* > \endverbatim */
/* > */
/* > \param[in] A */
/* > \verbatim */
/* > A is REAL array, dimension (LDA,N) */
/* > The factors L and U from the factorization A = P*L*U */
/* > as computed by SGETRF. */
/* > \endverbatim */
/* > */
/* > \param[in] LDA */
/* > \verbatim */
/* > LDA is INTEGER */
/* > The leading dimension of the array A. LDA >= max(1,N). */
/* > \endverbatim */
/* > */
/* > \param[in] ANORM */
/* > \verbatim */
/* > ANORM is REAL */
/* > If NORM = '1' or 'O', the 1-norm of the original matrix A. */
/* > If NORM = 'I', the infinity-norm of the original matrix A. */
/* > \endverbatim */
/* > */
/* > \param[out] RCOND */
/* > \verbatim */
/* > RCOND is REAL */
/* > The reciprocal of the condition number of the matrix A, */
/* > computed as RCOND = 1/(norm(A) * norm(inv(A))). */
/* > \endverbatim */
/* > */
/* > \param[out] WORK */
/* > \verbatim */
/* > WORK is REAL array, dimension (4*N) */
/* > \endverbatim */
/* > */
/* > \param[out] IWORK */
/* > \verbatim */
/* > IWORK is INTEGER array, dimension (N) */
/* > \endverbatim */
/* > */
/* > \param[out] INFO */
/* > \verbatim */
/* > INFO is INTEGER */
/* > = 0: successful exit */
/* > < 0: if INFO = -i, the i-th argument had an illegal value */
/* > \endverbatim */
/* Authors: */
/* ======== */
/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */
/* > \date November 2011 */
/* > \ingroup realGEcomputational */
/* ===================================================================== */
/* Subroutine */
int sgecon_(char *norm, integer *n, real *a, integer *lda, real *anorm, real *rcond, real *work, integer *iwork, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1;
real r__1;
/* Local variables */
real sl;
integer ix;
real su;
integer kase, kase1;
real scale;
extern logical lsame_(char *, char *);
integer isave[3];
extern /* Subroutine */
int srscl_(integer *, real *, real *, integer *), slacn2_(integer *, real *, real *, integer *, real *, integer *, integer *);
extern real slamch_(char *);
extern /* Subroutine */
int xerbla_(char *, integer *);
extern integer isamax_(integer *, real *, integer *);
real ainvnm;
logical onenrm;
char normin[1];
extern /* Subroutine */
int slatrs_(char *, char *, char *, char *, integer *, real *, integer *, real *, real *, real *, integer *);
real smlnum;
/* -- LAPACK computational routine (version 3.4.0) -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* November 2011 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. Local Arrays .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input parameters. */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--work;
--iwork;
/* Function Body */
*info = 0;
onenrm = *(unsigned char *)norm == '1' || lsame_(norm, "O");
if (! onenrm && ! lsame_(norm, "I"))
{
*info = -1;
}
else if (*n < 0)
{
*info = -2;
}
else if (*lda < max(1,*n))
{
*info = -4;
}
else if (*anorm < 0.f)
{
*info = -5;
}
if (*info != 0)
{
i__1 = -(*info);
xerbla_("SGECON", &i__1);
return 0;
}
/* Quick return if possible */
*rcond = 0.f;
if (*n == 0)
{
*rcond = 1.f;
return 0;
}
else if (*anorm == 0.f)
{
return 0;
}
smlnum = slamch_("Safe minimum");
/* Estimate the norm of inv(A). */
ainvnm = 0.f;
*(unsigned char *)normin = 'N';
if (onenrm)
{
kase1 = 1;
}
else
{
kase1 = 2;
}
kase = 0;
L10:
slacn2_(n, &work[*n + 1], &work[1], &iwork[1], &ainvnm, &kase, isave);
if (kase != 0)
{
if (kase == kase1)
{
/* Multiply by inv(L). */
slatrs_("Lower", "No transpose", "Unit", normin, n, &a[a_offset], lda, &work[1], &sl, &work[(*n << 1) + 1], info);
/* Multiply by inv(U). */
slatrs_("Upper", "No transpose", "Non-unit", normin, n, &a[ a_offset], lda, &work[1], &su, &work[*n * 3 + 1], info);
}
else
{
/* Multiply by inv(U**T). */
slatrs_("Upper", "Transpose", "Non-unit", normin, n, &a[a_offset], lda, &work[1], &su, &work[*n * 3 + 1], info);
/* Multiply by inv(L**T). */
slatrs_("Lower", "Transpose", "Unit", normin, n, &a[a_offset], lda, &work[1], &sl, &work[(*n << 1) + 1], info);
}
/* Divide X by 1/(SL*SU) if doing so will not cause overflow. */
scale = sl * su;
*(unsigned char *)normin = 'Y';
if (scale != 1.f)
{
ix = isamax_(n, &work[1], &c__1);
if (scale < (r__1 = work[ix], f2c_abs(r__1)) * smlnum || scale == 0.f)
{
goto L20;
}
srscl_(n, &scale, &work[1], &c__1);
}
goto L10;
}
/* Compute the estimate of the reciprocal condition number. */
if (ainvnm != 0.f)
{
*rcond = 1.f / ainvnm / *anorm;
}
L20:
return 0;
/* End of SGECON */
}
/* sgecon_ */
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