Chris@202: /* dgetf2.f -- translated by f2c (version 20061008).
Chris@202:    You must link the resulting object file with libf2c:
Chris@202: 	on Microsoft Windows system, link with libf2c.lib;
Chris@202: 	on Linux or Unix systems, link with .../path/to/libf2c.a -lm
Chris@202: 	or, if you install libf2c.a in a standard place, with -lf2c -lm
Chris@202: 	-- in that order, at the end of the command line, as in
Chris@202: 		cc *.o -lf2c -lm
Chris@202: 	Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
Chris@202: 
Chris@202: 		http://www.netlib.org/f2c/libf2c.zip
Chris@202: */
Chris@202: 
Chris@202: #include "f2c.h"
Chris@202: #include "blaswrap.h"
Chris@202: 
Chris@202: /* Table of constant values */
Chris@202: 
Chris@202: static integer c__1 = 1;
Chris@202: static doublereal c_b8 = -1.;
Chris@202: 
Chris@202: /* Subroutine */ int dgetf2_(integer *m, integer *n, doublereal *a, integer *
Chris@202: 	lda, integer *ipiv, integer *info)
Chris@202: {
Chris@202:     /* System generated locals */
Chris@202:     integer a_dim1, a_offset, i__1, i__2, i__3;
Chris@202:     doublereal d__1;
Chris@202: 
Chris@202:     /* Local variables */
Chris@202:     integer i__, j, jp;
Chris@202:     extern /* Subroutine */ int dger_(integer *, integer *, doublereal *, 
Chris@202: 	    doublereal *, integer *, doublereal *, integer *, doublereal *, 
Chris@202: 	    integer *), dscal_(integer *, doublereal *, doublereal *, integer 
Chris@202: 	    *);
Chris@202:     doublereal sfmin;
Chris@202:     extern /* Subroutine */ int dswap_(integer *, doublereal *, integer *, 
Chris@202: 	    doublereal *, integer *);
Chris@202:     extern doublereal dlamch_(char *);
Chris@202:     extern integer idamax_(integer *, doublereal *, integer *);
Chris@202:     extern /* Subroutine */ int xerbla_(char *, integer *);
Chris@202: 
Chris@202: 
Chris@202: /*  -- LAPACK routine (version 3.2) -- */
Chris@202: /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
Chris@202: /*     November 2006 */
Chris@202: 
Chris@202: /*     .. Scalar Arguments .. */
Chris@202: /*     .. */
Chris@202: /*     .. Array Arguments .. */
Chris@202: /*     .. */
Chris@202: 
Chris@202: /*  Purpose */
Chris@202: /*  ======= */
Chris@202: 
Chris@202: /*  DGETF2 computes an LU factorization of a general m-by-n matrix A */
Chris@202: /*  using partial pivoting with row interchanges. */
Chris@202: 
Chris@202: /*  The factorization has the form */
Chris@202: /*     A = P * L * U */
Chris@202: /*  where P is a permutation matrix, L is lower triangular with unit */
Chris@202: /*  diagonal elements (lower trapezoidal if m > n), and U is upper */
Chris@202: /*  triangular (upper trapezoidal if m < n). */
Chris@202: 
Chris@202: /*  This is the right-looking Level 2 BLAS version of the algorithm. */
Chris@202: 
Chris@202: /*  Arguments */
Chris@202: /*  ========= */
Chris@202: 
Chris@202: /*  M       (input) INTEGER */
Chris@202: /*          The number of rows of the matrix A.  M >= 0. */
Chris@202: 
Chris@202: /*  N       (input) INTEGER */
Chris@202: /*          The number of columns of the matrix A.  N >= 0. */
Chris@202: 
Chris@202: /*  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N) */
Chris@202: /*          On entry, the m by n matrix to be factored. */
Chris@202: /*          On exit, the factors L and U from the factorization */
Chris@202: /*          A = P*L*U; the unit diagonal elements of L are not stored. */
Chris@202: 
Chris@202: /*  LDA     (input) INTEGER */
Chris@202: /*          The leading dimension of the array A.  LDA >= max(1,M). */
Chris@202: 
Chris@202: /*  IPIV    (output) INTEGER array, dimension (min(M,N)) */
Chris@202: /*          The pivot indices; for 1 <= i <= min(M,N), row i of the */
Chris@202: /*          matrix was interchanged with row IPIV(i). */
Chris@202: 
Chris@202: /*  INFO    (output) INTEGER */
Chris@202: /*          = 0: successful exit */
Chris@202: /*          < 0: if INFO = -k, the k-th argument had an illegal value */
Chris@202: /*          > 0: if INFO = k, U(k,k) is exactly zero. The factorization */
Chris@202: /*               has been completed, but the factor U is exactly */
Chris@202: /*               singular, and division by zero will occur if it is used */
Chris@202: /*               to solve a system of equations. */
Chris@202: 
Chris@202: /*  ===================================================================== */
Chris@202: 
Chris@202: /*     .. Parameters .. */
Chris@202: /*     .. */
Chris@202: /*     .. Local Scalars .. */
Chris@202: /*     .. */
Chris@202: /*     .. External Functions .. */
Chris@202: /*     .. */
Chris@202: /*     .. External Subroutines .. */
Chris@202: /*     .. */
Chris@202: /*     .. Intrinsic Functions .. */
Chris@202: /*     .. */
Chris@202: /*     .. Executable Statements .. */
Chris@202: 
Chris@202: /*     Test the input parameters. */
Chris@202: 
Chris@202:     /* Parameter adjustments */
Chris@202:     a_dim1 = *lda;
Chris@202:     a_offset = 1 + a_dim1;
Chris@202:     a -= a_offset;
Chris@202:     --ipiv;
Chris@202: 
Chris@202:     /* Function Body */
Chris@202:     *info = 0;
Chris@202:     if (*m < 0) {
Chris@202: 	*info = -1;
Chris@202:     } else if (*n < 0) {
Chris@202: 	*info = -2;
Chris@202:     } else if (*lda < max(1,*m)) {
Chris@202: 	*info = -4;
Chris@202:     }
Chris@202:     if (*info != 0) {
Chris@202: 	i__1 = -(*info);
Chris@202: 	xerbla_("DGETF2", &i__1);
Chris@202: 	return 0;
Chris@202:     }
Chris@202: 
Chris@202: /*     Quick return if possible */
Chris@202: 
Chris@202:     if (*m == 0 || *n == 0) {
Chris@202: 	return 0;
Chris@202:     }
Chris@202: 
Chris@202: /*     Compute machine safe minimum */
Chris@202: 
Chris@202:     sfmin = dlamch_("S");
Chris@202: 
Chris@202:     i__1 = min(*m,*n);
Chris@202:     for (j = 1; j <= i__1; ++j) {
Chris@202: 
Chris@202: /*        Find pivot and test for singularity. */
Chris@202: 
Chris@202: 	i__2 = *m - j + 1;
Chris@202: 	jp = j - 1 + idamax_(&i__2, &a[j + j * a_dim1], &c__1);
Chris@202: 	ipiv[j] = jp;
Chris@202: 	if (a[jp + j * a_dim1] != 0.) {
Chris@202: 
Chris@202: /*           Apply the interchange to columns 1:N. */
Chris@202: 
Chris@202: 	    if (jp != j) {
Chris@202: 		dswap_(n, &a[j + a_dim1], lda, &a[jp + a_dim1], lda);
Chris@202: 	    }
Chris@202: 
Chris@202: /*           Compute elements J+1:M of J-th column. */
Chris@202: 
Chris@202: 	    if (j < *m) {
Chris@202: 		if ((d__1 = a[j + j * a_dim1], abs(d__1)) >= sfmin) {
Chris@202: 		    i__2 = *m - j;
Chris@202: 		    d__1 = 1. / a[j + j * a_dim1];
Chris@202: 		    dscal_(&i__2, &d__1, &a[j + 1 + j * a_dim1], &c__1);
Chris@202: 		} else {
Chris@202: 		    i__2 = *m - j;
Chris@202: 		    for (i__ = 1; i__ <= i__2; ++i__) {
Chris@202: 			a[j + i__ + j * a_dim1] /= a[j + j * a_dim1];
Chris@202: /* L20: */
Chris@202: 		    }
Chris@202: 		}
Chris@202: 	    }
Chris@202: 
Chris@202: 	} else if (*info == 0) {
Chris@202: 
Chris@202: 	    *info = j;
Chris@202: 	}
Chris@202: 
Chris@202: 	if (j < min(*m,*n)) {
Chris@202: 
Chris@202: /*           Update trailing submatrix. */
Chris@202: 
Chris@202: 	    i__2 = *m - j;
Chris@202: 	    i__3 = *n - j;
Chris@202: 	    dger_(&i__2, &i__3, &c_b8, &a[j + 1 + j * a_dim1], &c__1, &a[j + (
Chris@202: 		    j + 1) * a_dim1], lda, &a[j + 1 + (j + 1) * a_dim1], lda);
Chris@202: 	}
Chris@202: /* L10: */
Chris@202:     }
Chris@202:     return 0;
Chris@202: 
Chris@202: /*     End of DGETF2 */
Chris@202: 
Chris@202: } /* dgetf2_ */