dormql.c

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#include "gmx_lapack.h"
#include "lapack_limits.h"

void
F77_FUNC(dormql,DORMQL)(char *side, char *trans, int *m, int *n, 
	int *k, double *a, int *lda, double *tau, double *
	c__, int *ldc, double *work, int *lwork, int *info)
{
    int a_dim1, a_offset, c_dim1, c_offset, i__1, i__2, i__4, i__5;
    int c__65 = 65;

    int i__;
    double t[4160];
    int i1, i2, i3, ib, nb, mi, ni, nq, nw, iws;
    int left;
    int nbmin, iinfo;
    int notran;
    int ldwork, lwkopt;
    int lquery;


    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --tau;
    c_dim1 = *ldc;
    c_offset = 1 + c_dim1;
    c__ -= c_offset;
    --work;

    *info = 0;
    left = (*side=='L' || *side=='l');
    notran = (*trans=='N' || *trans=='n');
    lquery = *lwork == -1;

    if (left) {
	nq = *m;
	nw = *n;
    } else {
	nq = *n;
	nw = *m;
    }

    nb = DORMQL_BLOCKSIZE;
    lwkopt = nw * nb;
    work[1] = (double) lwkopt;
    
    if (*info != 0) {
	i__1 = -(*info);
	return;
    } else if (lquery) {
	return;
    }

    if (*m == 0 || *n == 0 || *k == 0) {
	work[1] = 1.;
	return;
    }

    nbmin = 2;
    ldwork = nw;
    if (nb > 1 && nb < *k) {
	iws = nw * nb;
	if (*lwork < iws) {
	    nb = *lwork / ldwork;
	    nbmin = DORMQL_MINBLOCKSIZE;
	}
    } else {
	iws = nw;
    }

    if (nb < nbmin || nb >= *k) {

	F77_FUNC(dorm2l,DORM2L)(side, trans, m, n, k, &a[a_offset], lda, &tau[1], &c__[
		c_offset], ldc, &work[1], &iinfo);
    } else {

	if ((left && notran) || (! left && ! notran)) {
	    i1 = 1;
	    i2 = *k;
	    i3 = nb;
	} else {
	    i1 = (*k - 1) / nb * nb + 1;
	    i2 = 1;
	    i3 = -nb;
	}

	if (left) {
	    ni = *n;
	} else {
	    mi = *m;
	}

	i__1 = i2;
	i__2 = i3;
	for (i__ = i1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) {
	    i__4 = nb, i__5 = *k - i__ + 1;
	    ib = (i__4<i__5) ? i__4 : i__5;

	    i__4 = nq - *k + i__ + ib - 1;
	    F77_FUNC(dlarft,DLARFT)("Backward", "Columnwise", &i__4, &ib, &a[i__ * a_dim1 + 1]
		    , lda, &tau[i__], t, &c__65);
	    if (left) {

		mi = *m - *k + i__ + ib - 1;
	    } else {

		ni = *n - *k + i__ + ib - 1;
	    }

	    F77_FUNC(dlarfb,DLARFB)(side, trans, "Backward", "Columnwise", &mi, &ni, &ib, &a[
		    i__ * a_dim1 + 1], lda, t, &c__65, &c__[c_offset], ldc, &
		    work[1], &ldwork);
	}
    }
    work[1] = (double) lwkopt;
    return;

}