sorgl2.c File Reference

(r)

Functions
int	sorgl2_fla (integer *m, integer *n, integer *k, real *a, integer *lda, real *tau, real *work, integer *info)

Function Documentation

sorgl2_fla()

int sorgl2_fla	(	integer *	m,
		integer *	n,
		integer *	k,
		real *	a,
		integer *	lda,
		real *	tau,
		real *	work,
		integer *	info
	)

{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2;
    real r__1;
    /* Local variables */
    integer i__, j, l;
    extern /* Subroutine */
    int sscal_(integer *, real *, real *, integer *), slarf_(char *, integer *, integer *, real *, integer *, real *, real *, integer *, real *), xerbla_(char *, integer *);
    /* -- 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 .. */
    /* .. */
    /* .. 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;
    if (*m < 0)
    {
        *info = -1;
    }
    else if (*n < *m)
    {
        *info = -2;
    }
    else if (*k < 0 || *k > *m)
    {
        *info = -3;
    }
    else if (*lda < max(1,*m))
    {
        *info = -5;
    }
    if (*info != 0)
    {
        i__1 = -(*info);
        xerbla_("SORGL2", &i__1);
        return 0;
    }
    /* Quick return if possible */
    if (*m <= 0)
    {
        return 0;
    }
    if (*k < *m)
    {
        /* Initialise rows k+1:m to rows of the unit matrix */
        i__1 = *n;
        for (j = 1;
                j <= i__1;
                ++j)
        {
            i__2 = *m;
            for (l = *k + 1;
                    l <= i__2;
                    ++l)
            {
                a[l + j * a_dim1] = 0.f;
                /* L10: */
            }
            if (j > *k && j <= *m)
            {
                a[j + j * a_dim1] = 1.f;
            }
            /* L20: */
        }
    }
    for (i__ = *k;
            i__ >= 1;
            --i__)
    {
        /* Apply H(i) to A(i:m,i:n) from the right */
        if (i__ < *n)
        {
            if (i__ < *m)
            {
                a[i__ + i__ * a_dim1] = 1.f;
                i__1 = *m - i__;
                i__2 = *n - i__ + 1;
                slarf_("Right", &i__1, &i__2, &a[i__ + i__ * a_dim1], lda, & tau[i__], &a[i__ + 1 + i__ * a_dim1], lda, &work[1]);
            }
            i__1 = *n - i__;
            r__1 = -tau[i__];
            sscal_(&i__1, &r__1, &a[i__ + (i__ + 1) * a_dim1], lda);
        }
        a[i__ + i__ * a_dim1] = 1.f - tau[i__];
        /* Set A(i,1:i-1) to zero */
        i__1 = i__ - 1;
        for (l = 1;
                l <= i__1;
                ++l)
        {
            a[i__ + l * a_dim1] = 0.f;
            /* L30: */
        }
        /* L40: */
    }
    return 0;
    /* End of SORGL2 */
}

References i.

Referenced by sorglq_fla().