dormlq.c File Reference

(r)

Functions
int	dormlq_fla (char *side, char *trans, integer *m, integer *n, integer *k, doublereal *a, integer *lda, doublereal *tau, doublereal *c__, integer *ldc, doublereal *work, integer *lwork, integer *info)

Function Documentation

dormlq_fla()

int dormlq_fla	(	char *	side,
		char *	trans,
		integer *	m,
		integer *	n,
		integer *	k,
		doublereal *	a,
		integer *	lda,
		doublereal *	tau,
		doublereal *	c__,
		integer *	ldc,
		doublereal *	work,
		integer *	lwork,
		integer *	info )

{
    /* System generated locals */
    integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2, i__4, i__5;
    char ch__1[2];
    /* Builtin functions */
    /* Subroutine */
 
    /* Local variables */
    integer i__;
    doublereal t[4160] /* was [65][64] */
    ;
    integer i1, i2, i3, ib, ic, jc, nb, mi, ni, nq, nw, iws;
    logical left;
    extern logical lsame_(char *, char *);
    integer nbmin, iinfo;
    extern /* Subroutine */
    int dorml2_fla(char *, char *, integer *, integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *, doublereal *, integer *), dlarfb_(char *, char *, char *, char *, integer *, integer *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *), dlarft_(char *, char *, integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *), xerbla_(char *, integer *);
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *);
    logical notran;
    integer ldwork;
    char transt[1];
    integer lwkopt;
    logical lquery;
    /* -- LAPACK computational routine (version 3.4.0) -- */
    /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
    /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
    /* November 2011 */
    /* .. Scalar Arguments .. */
    /* .. */
    /* .. Array Arguments .. */
    /* .. */
    /* ===================================================================== */
    /* .. Parameters .. */
    /* .. */
    /* .. Local Scalars .. */
    /* .. */
    /* .. Local Arrays .. */
    /* .. */
    /* .. External Functions .. */
    /* .. */
    /* .. External Subroutines .. */
    /* .. */
    /* .. Intrinsic Functions .. */
    /* .. */
    /* .. Executable Statements .. */
    /* Test the input arguments */
    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --tau;
    c_dim1 = *ldc;
    c_offset = 1 + c_dim1;
    c__ -= c_offset;
    --work;
    /* Function Body */
    *info = 0;
    left = lsame_(side, "L");
    notran = lsame_(trans, "N");
    lquery = *lwork == -1;
    /* NQ is the order of Q and NW is the minimum dimension of WORK */
    if (left)
    {
        nq = *m;
        nw = *n;
    }
    else
    {
        nq = *n;
        nw = *m;
    }
    if (! left && ! lsame_(side, "R"))
    {
        *info = -1;
    }
    else if (! notran && ! lsame_(trans, "T"))
    {
        *info = -2;
    }
    else if (*m < 0)
    {
        *info = -3;
    }
    else if (*n < 0)
    {
        *info = -4;
    }
    else if (*k < 0 || *k > nq)
    {
        *info = -5;
    }
    else if (*lda < max(1,*k))
    {
        *info = -7;
    }
    else if (*ldc < max(1,*m))
    {
        *info = -10;
    }
    else if (*lwork < max(1,nw) && ! lquery)
    {
        *info = -12;
    }
    if (*info == 0)
    {
        /* Determine the block size. NB may be at most NBMAX, where NBMAX */
        /* is used to define the local array T. */
        /* Computing MIN */
        i__1 = 64;
        i__2 = ilaenv_(&c__1, "DORMLQ", ch__1, m, n, k, &c_n1); // , expr subst
        nb = min(i__1,i__2);
        lwkopt = max(1,nw) * nb;
        work[1] = (doublereal) lwkopt;
    }
    if (*info != 0)
    {
        i__1 = -(*info);
        xerbla_("DORMLQ", &i__1);
        return 0;
    }
    else if (lquery)
    {
        return 0;
    }
    /* Quick return if possible */
    if (*m == 0 || *n == 0 || *k == 0)
    {
        work[1] = 1.;
        return 0;
    }
    nbmin = 2;
    ldwork = nw;
    if (nb > 1 && nb < *k)
    {
        iws = nw * nb;
        if (*lwork < iws)
        {
            nb = *lwork / ldwork;
            /* Computing MAX */
            i__1 = 2;
            i__2 = ilaenv_(&c__2, "DORMLQ", ch__1, m, n, k, &c_n1); // , expr subst
            nbmin = max(i__1,i__2);
        }
    }
    else
    {
        iws = nw;
    }
    if (nb < nbmin || nb >= *k)
    {
        /* Use unblocked code */
        dorml2_fla(side, trans, m, n, k, &a[a_offset], lda, &tau[1], &c__[ c_offset], ldc, &work[1], &iinfo);
    }
    else
    {
        /* Use blocked code */
        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;
            jc = 1;
        }
        else
        {
            mi = *m;
            ic = 1;
        }
        if (notran)
        {
            *(unsigned char *)transt = 'T';
        }
        else
        {
            *(unsigned char *)transt = 'N';
        }
        i__1 = i2;
        i__2 = i3;
        for (i__ = i1;
                i__2 < 0 ? i__ >= i__1 : i__ <= i__1;
                i__ += i__2)
        {
            /* Computing MIN */
            i__4 = nb;
            i__5 = *k - i__ + 1; // , expr subst
            ib = min(i__4,i__5);
            /* Form the triangular factor of the block reflector */
            /* H = H(i) H(i+1) . . . H(i+ib-1) */
            i__4 = nq - i__ + 1;
            dlarft_("Forward", "Rowwise", &i__4, &ib, &a[i__ + i__ * a_dim1], lda, &tau[i__], t, &c__65);
            if (left)
            {
                /* H or H**T is applied to C(i:m,1:n) */
                mi = *m - i__ + 1;
                ic = i__;
            }
            else
            {
                /* H or H**T is applied to C(1:m,i:n) */
                ni = *n - i__ + 1;
                jc = i__;
            }
            /* Apply H or H**T */
            dlarfb_(side, transt, "Forward", "Rowwise", &mi, &ni, &ib, &a[i__ + i__ * a_dim1], lda, t, &c__65, &c__[ic + jc * c_dim1], ldc, &work[1], &ldwork);
            /* L10: */
        }
    }
    work[1] = (doublereal) lwkopt;
    return 0;
    /* End of DORMLQ */
}

References dorml2_fla().