#include "blaswrap.h"
/* sgelqs.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 real c_b7 = 1.f;
static real c_b9 = 0.f;

/* Subroutine */ int sgelqs_(integer *m, integer *n, integer *nrhs, real *a, 
	integer *lda, real *tau, real *b, integer *ldb, real *work, integer *
	lwork, integer *info)
{
    /* System generated locals */
    integer a_dim1, a_offset, b_dim1, b_offset, i__1;

    /* Local variables */
    extern /* Subroutine */ int strsm_(char *, char *, char *, char *, 
	    integer *, integer *, real *, real *, integer *, real *, integer *
), xerbla_(char *, integer *), slaset_(char *, integer *, integer *, real *, real *, 
	    real *, integer *), sormlq_(char *, char *, integer *, 
	    integer *, integer *, real *, integer *, real *, real *, integer *
	    , real *, integer *, integer *);


/*  -- LAPACK routine (version 3.1) --   
       Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..   
       November 2006   


    Purpose   
    =======   

    Compute a minimum-norm solution   
        min || A*X - B ||   
    using the LQ factorization   
        A = L*Q   
    computed by SGELQF.   

    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 >= M >= 0.   

    NRHS    (input) INTEGER   
            The number of columns of B.  NRHS >= 0.   

    A       (input) REAL array, dimension (LDA,N)   
            Details of the LQ factorization of the original matrix A as   
            returned by SGELQF.   

    LDA     (input) INTEGER   
            The leading dimension of the array A.  LDA >= M.   

    TAU     (input) REAL array, dimension (M)   
            Details of the orthogonal matrix Q.   

    B       (input/output) REAL array, dimension (LDB,NRHS)   
            On entry, the m-by-nrhs right hand side matrix B.   
            On exit, the n-by-nrhs solution matrix X.   

    LDB     (input) INTEGER   
            The leading dimension of the array B. LDB >= N.   

    WORK    (workspace) REAL array, dimension (LWORK)   

    LWORK   (input) INTEGER   
            The length of the array WORK.  LWORK must be at least NRHS,   
            and should be at least NRHS*NB, where NB is the block size   
            for this environment.   

    INFO    (output) INTEGER   
            = 0: successful exit   
            < 0: if INFO = -i, the i-th argument had an illegal value   

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


       Test the input parameters.   

       Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --tau;
    b_dim1 = *ldb;
    b_offset = 1 + b_dim1;
    b -= b_offset;
    --work;

    /* Function Body */
    *info = 0;
    if (*m < 0) {
	*info = -1;
    } else if (*n < 0 || *m > *n) {
	*info = -2;
    } else if (*nrhs < 0) {
	*info = -3;
    } else if (*lda < max(1,*m)) {
	*info = -5;
    } else if (*ldb < max(1,*n)) {
	*info = -8;
    } else if (*lwork < 1 || *lwork < *nrhs && *m > 0 && *n > 0) {
	*info = -10;
    }
    if (*info != 0) {
	i__1 = -(*info);
	xerbla_("SGELQS", &i__1);
	return 0;
    }

/*     Quick return if possible */

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

/*     Solve L*X = B(1:m,:) */

    strsm_("Left", "Lower", "No transpose", "Non-unit", m, nrhs, &c_b7, &a[
	    a_offset], lda, &b[b_offset], ldb);

/*     Set B(m+1:n,:) to zero */

    if (*m < *n) {
	i__1 = *n - *m;
	slaset_("Full", &i__1, nrhs, &c_b9, &c_b9, &b[*m + 1 + b_dim1], ldb);
    }

/*     B := Q' * B */

    sormlq_("Left", "Transpose", n, nrhs, m, &a[a_offset], lda, &tau[1], &b[
	    b_offset], ldb, &work[1], lwork, info);

    return 0;

/*     End of SGELQS */

} /* sgelqs_ */