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/* sgetrf.f -- translated by f2c (version 20061008).
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 "f2c.h"
#include "blaswrap.h"
/* Table of constant values */
static integer c__1 = 1;
static integer c_n1 = -1;
static real c_b16 = 1.f;
static real c_b19 = -1.f;
/* Subroutine */ int sgetrf_(integer *m, integer *n, real *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, iinfo;
extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *,
integer *, real *, real *, integer *, real *, integer *, real *,
real *, integer *), strsm_(char *, char *, char *,
char *, integer *, integer *, real *, real *, integer *, real *,
integer *), sgetf2_(integer *,
integer *, real *, integer *, integer *, integer *), xerbla_(char
*, integer *);
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *);
extern /* Subroutine */ int slaswp_(integer *, real *, integer *, integer
*, integer *, integer *, integer *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* SGETRF 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. */
/* Arguments */
/* ========= */
/* M (input) INTEGER */
/* The number of rows of the matrix A. M >= 0. */
/* N (input) INTEGER */
/* The number of columns of the matrix A. N >= 0. */
/* A (input/output) REAL 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. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= max(1,M). */
/* IPIV (output) 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). */
/* INFO (output) 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. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* 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);
xerbla_("SGETRF", &i__1);
return 0;
}
/* Quick return if possible */
if (*m == 0 || *n == 0) {
return 0;
}
/* Determine the block size for this environment. */
nb = ilaenv_(&c__1, "SGETRF", " ", m, n, &c_n1, &c_n1);
if (nb <= 1 || nb >= min(*m,*n)) {
/* Use unblocked code. */
sgetf2_(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;
sgetf2_(&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;
slaswp_(&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;
slaswp_(&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;
strsm_("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;
sgemm_("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 SGETRF */
} /* sgetrf_ */
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