dorghr.c File Reference

(r)

Functions
int	dorghr_ (integer *n, integer *ilo, integer *ihi, doublereal *a, integer *lda, doublereal *tau, doublereal *work, integer *lwork, integer *info)

Function Documentation

dorghr_()

int dorghr_	(	integer *	n,
		integer *	ilo,
		integer *	ihi,
		doublereal *	a,
		integer *	lda,
		doublereal *	tau,
		doublereal *	work,
		integer *	lwork,
		integer *	info )

{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2;
    /* Local variables */
    integer i__, j, nb, nh, iinfo;
    extern /* Subroutine */
    int xerbla_(char *, integer *);
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *);
    extern /* Subroutine */
    int dorgqr_fla(integer *, integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *, integer *);
    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 .. */
    /* .. */
    /* .. External Subroutines .. */
    /* .. */
    /* .. External Functions .. */
    /* .. */
    /* .. Intrinsic Functions .. */
    /* .. */
    /* .. Executable Statements .. */
    /* Test the input arguments */
    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --tau;
    --work;
    /* Function Body */
    *info = 0;
    nh = *ihi - *ilo;
    lquery = *lwork == -1;
    if (*n < 0)
    {
        *info = -1;
    }
    else if (*ilo < 1 || *ilo > max(1,*n))
    {
        *info = -2;
    }
    else if (*ihi < min(*ilo,*n) || *ihi > *n)
    {
        *info = -3;
    }
    else if (*lda < max(1,*n))
    {
        *info = -5;
    }
    else if (*lwork < max(1,nh) && ! lquery)
    {
        *info = -8;
    }
    if (*info == 0)
    {
        nb = ilaenv_(&c__1, "DORGQR", " ", &nh, &nh, &nh, &c_n1);
        lwkopt = max(1,nh) * nb;
        work[1] = (doublereal) lwkopt;
    }
    if (*info != 0)
    {
        i__1 = -(*info);
        xerbla_("DORGHR", &i__1);
        return 0;
    }
    else if (lquery)
    {
        return 0;
    }
    /* Quick return if possible */
    if (*n == 0)
    {
        work[1] = 1.;
        return 0;
    }
    /* Shift the vectors which define the elementary reflectors one */
    /* column to the right, and set the first ilo and the last n-ihi */
    /* rows and columns to those of the unit matrix */
    i__1 = *ilo + 1;
    for (j = *ihi;
            j >= i__1;
            --j)
    {
        i__2 = j - 1;
        for (i__ = 1;
                i__ <= i__2;
                ++i__)
        {
            a[i__ + j * a_dim1] = 0.;
            /* L10: */
        }
        i__2 = *ihi;
        for (i__ = j + 1;
                i__ <= i__2;
                ++i__)
        {
            a[i__ + j * a_dim1] = a[i__ + (j - 1) * a_dim1];
            /* L20: */
        }
        i__2 = *n;
        for (i__ = *ihi + 1;
                i__ <= i__2;
                ++i__)
        {
            a[i__ + j * a_dim1] = 0.;
            /* L30: */
        }
        /* L40: */
    }
    i__1 = *ilo;
    for (j = 1;
            j <= i__1;
            ++j)
    {
        i__2 = *n;
        for (i__ = 1;
                i__ <= i__2;
                ++i__)
        {
            a[i__ + j * a_dim1] = 0.;
            /* L50: */
        }
        a[j + j * a_dim1] = 1.;
        /* L60: */
    }
    i__1 = *n;
    for (j = *ihi + 1;
            j <= i__1;
            ++j)
    {
        i__2 = *n;
        for (i__ = 1;
                i__ <= i__2;
                ++i__)
        {
            a[i__ + j * a_dim1] = 0.;
            /* L70: */
        }
        a[j + j * a_dim1] = 1.;
        /* L80: */
    }
    if (nh > 0)
    {
        /* Generate Q(ilo+1:ihi,ilo+1:ihi) */
        dorgqr_fla(&nh, &nh, &nh, &a[*ilo + 1 + (*ilo + 1) * a_dim1], lda, &tau[* ilo], &work[1], lwork, &iinfo);
    }
    work[1] = (doublereal) lwkopt;
    return 0;
    /* End of DORGHR */
}

References dorgqr_fla().