/* -- 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
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*/
#include "f2c.h"
/* Table of constant values */
static integer c__1 = 1;
static integer c_n1 = -1;
static doublereal c_b16 = 1.;
static doublereal c_b19 = -1.;
/* > \brief \b DGETRF
=========== DOCUMENTATION ===========
Online html documentation available at
http://www.netlib.org/lapack/explore-html/
> \htmlonly
> Download DGETRF + dependencies
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgetrf.
f">
> [TGZ]</a>
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgetrf.
f">
> [ZIP]</a>
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgetrf.
f">
> [TXT]</a>
> \endhtmlonly
Definition:
===========
SUBROUTINE DGETRF( M, N, A, LDA, IPIV, INFO )
INTEGER INFO, LDA, M, N
INTEGER IPIV( * )
DOUBLE PRECISION A( LDA, * )
> \par Purpose:
=============
>
> \verbatim
>
> DGETRF computes an LU factorization of a general M-by-N matrix A
> using partial pivoting with row interchanges.
>
> The factorization has the form
> A = P * L * U
> where P is a permutation matrix, L is lower triangular with unit
> diagonal elements (lower trapezoidal if m > n), and U is upper
> triangular (upper trapezoidal if m < n).
>
> This is the right-looking Level 3 BLAS version of the algorithm.
> \endverbatim
Arguments:
==========
> \param[in] M
> \verbatim
> M is INTEGER
> The number of rows of the matrix A. M >= 0.
> \endverbatim
>
> \param[in] N
> \verbatim
> N is INTEGER
> The number of columns of the matrix A. N >= 0.
> \endverbatim
>
> \param[in,out] A
> \verbatim
> A is DOUBLE PRECISION array, dimension (LDA,N)
> On entry, the M-by-N matrix to be factored.
> On exit, the factors L and U from the factorization
> A = P*L*U; the unit diagonal elements of L are not stored.
> \endverbatim
>
> \param[in] LDA
> \verbatim
> LDA is INTEGER
> The leading dimension of the array A. LDA >= max(1,M).
> \endverbatim
>
> \param[out] IPIV
> \verbatim
> IPIV is INTEGER array, dimension (min(M,N))
> The pivot indices; for 1 <= i <= min(M,N), row i of the
> matrix was interchanged with row IPIV(i).
> \endverbatim
>
> \param[out] INFO
> \verbatim
> INFO is INTEGER
> = 0: successful exit
> < 0: if INFO = -i, the i-th argument had an illegal value
> > 0: if INFO = i, U(i,i) is exactly zero. The factorization
> has been completed, but the factor U is exactly
> singular, and division by zero will occur if it is used
> to solve a system of equations.
> \endverbatim
Authors:
========
> \author Univ. of Tennessee
> \author Univ. of California Berkeley
> \author Univ. of Colorado Denver
> \author NAG Ltd.
> \date November 2011
> \ingroup doubleGEcomputational
=====================================================================
Subroutine */ int igraphdgetrf_(integer *m, integer *n, doublereal *a, integer *
lda, integer *ipiv, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3, i__4, i__5;
/* Local variables */
integer i__, j, jb, nb;
extern /* Subroutine */ int igraphdgemm_(char *, char *, integer *, integer *,
integer *, doublereal *, doublereal *, integer *, doublereal *,
integer *, doublereal *, doublereal *, integer *);
integer iinfo;
extern /* Subroutine */ int igraphdtrsm_(char *, char *, char *, char *,
integer *, integer *, doublereal *, doublereal *, integer *,
doublereal *, integer *), igraphdgetf2_(
integer *, integer *, doublereal *, integer *, integer *, integer
*), igraphxerbla_(char *, integer *, ftnlen);
extern integer igraphilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *, ftnlen, ftnlen);
extern /* Subroutine */ int igraphdlaswp_(integer *, doublereal *, integer *,
integer *, integer *, integer *, integer *);
/* -- 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
=====================================================================
Test the input parameters.
Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--ipiv;
/* Function Body */
*info = 0;
if (*m < 0) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*lda < max(1,*m)) {
*info = -4;
}
if (*info != 0) {
i__1 = -(*info);
igraphxerbla_("DGETRF", &i__1, (ftnlen)6);
return 0;
}
/* Quick return if possible */
if (*m == 0 || *n == 0) {
return 0;
}
/* Determine the block size for this environment. */
nb = igraphilaenv_(&c__1, "DGETRF", " ", m, n, &c_n1, &c_n1, (ftnlen)6, (ftnlen)
1);
if (nb <= 1 || nb >= min(*m,*n)) {
/* Use unblocked code. */
igraphdgetf2_(m, n, &a[a_offset], lda, &ipiv[1], info);
} else {
/* Use blocked code. */
i__1 = min(*m,*n);
i__2 = nb;
for (j = 1; i__2 < 0 ? j >= i__1 : j <= i__1; j += i__2) {
/* Computing MIN */
i__3 = min(*m,*n) - j + 1;
jb = min(i__3,nb);
/* Factor diagonal and subdiagonal blocks and test for exact
singularity. */
i__3 = *m - j + 1;
igraphdgetf2_(&i__3, &jb, &a[j + j * a_dim1], lda, &ipiv[j], &iinfo);
/* Adjust INFO and the pivot indices. */
if (*info == 0 && iinfo > 0) {
*info = iinfo + j - 1;
}
/* Computing MIN */
i__4 = *m, i__5 = j + jb - 1;
i__3 = min(i__4,i__5);
for (i__ = j; i__ <= i__3; ++i__) {
ipiv[i__] = j - 1 + ipiv[i__];
/* L10: */
}
/* Apply interchanges to columns 1:J-1. */
i__3 = j - 1;
i__4 = j + jb - 1;
igraphdlaswp_(&i__3, &a[a_offset], lda, &j, &i__4, &ipiv[1], &c__1);
if (j + jb <= *n) {
/* Apply interchanges to columns J+JB:N. */
i__3 = *n - j - jb + 1;
i__4 = j + jb - 1;
igraphdlaswp_(&i__3, &a[(j + jb) * a_dim1 + 1], lda, &j, &i__4, &
ipiv[1], &c__1);
/* Compute block row of U. */
i__3 = *n - j - jb + 1;
igraphdtrsm_("Left", "Lower", "No transpose", "Unit", &jb, &i__3, &
c_b16, &a[j + j * a_dim1], lda, &a[j + (j + jb) *
a_dim1], lda);
if (j + jb <= *m) {
/* Update trailing submatrix. */
i__3 = *m - j - jb + 1;
i__4 = *n - j - jb + 1;
igraphdgemm_("No transpose", "No transpose", &i__3, &i__4, &jb,
&c_b19, &a[j + jb + j * a_dim1], lda, &a[j + (j +
jb) * a_dim1], lda, &c_b16, &a[j + jb + (j + jb) *
a_dim1], lda);
}
}
/* L20: */
}
}
return 0;
/* End of DGETRF */
} /* igraphdgetrf_ */