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/* ../../../dependencies/lapack/src/cgetf2.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"
/* Table of constant values */
static complex c_b1 = {1.f,0.f};
static integer c__1 = 1;
/* Subroutine */ int cgetf2_(integer *m, integer *n, complex *a, integer *lda,
integer *ipiv, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3;
complex q__1;
/* Builtin functions */
void c_div(complex *, complex *, complex *);
/* Local variables */
static integer j, jp;
extern /* Subroutine */ int cscal_(integer *, complex *, complex *,
integer *), cgeru_(integer *, integer *, complex *, complex *,
integer *, complex *, integer *, complex *, integer *), cswap_(
integer *, complex *, integer *, complex *, integer *);
extern integer icamax_(integer *, complex *, integer *);
extern /* Subroutine */ int xerbla_(char *, integer *, ftnlen);
/* -- LAPACK routine (version 3.0) -- */
/* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
/* Courant Institute, Argonne National Lab, and Rice University */
/* September 30, 1994 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* CGETF2 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 2 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) COMPLEX 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 = -k, the k-th argument had an illegal value */
/* > 0: if INFO = k, U(k,k) 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 Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. 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_("CGETF2", &i__1, (ftnlen)6);
return 0;
}
/* Quick return if possible */
if (*m == 0 || *n == 0) {
return 0;
}
i__1 = min(*m,*n);
for (j = 1; j <= i__1; ++j) {
/* Find pivot and test for singularity. */
i__2 = *m - j + 1;
jp = j - 1 + icamax_(&i__2, &a[j + j * a_dim1], &c__1);
ipiv[j] = jp;
i__2 = jp + j * a_dim1;
if (a[i__2].r != 0.f || a[i__2].i != 0.f) {
/* Apply the interchange to columns 1:N. */
if (jp != j) {
cswap_(n, &a[j + a_dim1], lda, &a[jp + a_dim1], lda);
}
/* Compute elements J+1:M of J-th column. */
if (j < *m) {
i__2 = *m - j;
c_div(&q__1, &c_b1, &a[j + j * a_dim1]);
cscal_(&i__2, &q__1, &a[j + 1 + j * a_dim1], &c__1);
}
} else if (*info == 0) {
*info = j;
}
if (j < min(*m,*n)) {
/* Update trailing submatrix. */
i__2 = *m - j;
i__3 = *n - j;
q__1.r = -1.f, q__1.i = -0.f;
cgeru_(&i__2, &i__3, &q__1, &a[j + 1 + j * a_dim1], &c__1, &a[j +
(j + 1) * a_dim1], lda, &a[j + 1 + (j + 1) * a_dim1], lda)
;
}
/* L10: */
}
return 0;
/* End of CGETF2 */
} /* cgetf2_ */
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