#include "blaswrap.h"
#include "f2c.h"

/* Subroutine */ int dgetf2_(integer *m, integer *n, doublereal *a, integer *
	lda, integer *ipiv, integer *info)
{
/*  -- LAPACK routine (version 3.1) --   
       Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..   
       November 2006   


    Purpose   
    =======   

    DGETF2 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) 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.   

    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.   

    =====================================================================   


       Test the input parameters.   

       Parameter adjustments */
    /* Table of constant values */
    static integer c__1 = 1;
    static doublereal c_b8 = -1.;
    
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2, i__3;
    doublereal d__1;
    /* Local variables */
    static integer i__, j, jp;
    extern /* Subroutine */ int dger_(integer *, integer *, doublereal *, 
	    doublereal *, integer *, doublereal *, integer *, doublereal *, 
	    integer *), dscal_(integer *, doublereal *, doublereal *, integer 
	    *);
    static doublereal sfmin;
    extern /* Subroutine */ int dswap_(integer *, doublereal *, integer *, 
	    doublereal *, integer *);
    extern doublereal dlamch_(char *);
    extern integer idamax_(integer *, doublereal *, integer *);
    extern /* Subroutine */ int xerbla_(char *, integer *);


    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_("DGETF2", &i__1);
	return 0;
    }

/*     Quick return if possible */

    if (*m == 0 || *n == 0) {
	return 0;
    }

/*     Compute machine safe minimum */

    sfmin = dlamch_("S");

    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 + idamax_(&i__2, &a[j + j * a_dim1], &c__1);
	ipiv[j] = jp;
	if (a[jp + j * a_dim1] != 0.) {

/*           Apply the interchange to columns 1:N. */

	    if (jp != j) {
		dswap_(n, &a[j + a_dim1], lda, &a[jp + a_dim1], lda);
	    }

/*           Compute elements J+1:M of J-th column. */

	    if (j < *m) {
		if ((d__1 = a[j + j * a_dim1], abs(d__1)) >= sfmin) {
		    i__2 = *m - j;
		    d__1 = 1. / a[j + j * a_dim1];
		    dscal_(&i__2, &d__1, &a[j + 1 + j * a_dim1], &c__1);
		} else {
		    i__2 = *m - j;
		    for (i__ = 1; i__ <= i__2; ++i__) {
			a[j + i__ + j * a_dim1] /= a[j + j * a_dim1];
/* L20: */
		    }
		}
	    }

	} else if (*info == 0) {

	    *info = j;
	}

	if (j < min(*m,*n)) {

/*           Update trailing submatrix. */

	    i__2 = *m - j;
	    i__3 = *n - j;
	    dger_(&i__2, &i__3, &c_b8, &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 DGETF2 */

} /* dgetf2_ */