cungl2.c File Reference

(r)

Functions
int	cungl2_fla (integer *m, integer *n, integer *k, complex *a, integer *lda, complex *tau, complex *work, integer *info)

Function Documentation

cungl2_fla()

int cungl2_fla	(	integer *	m,
		integer *	n,
		integer *	k,
		complex *	a,
		integer *	lda,
		complex *	tau,
		complex *	work,
		integer *	info )

{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2, i__3;
    complex q__1, q__2;
    /* Builtin functions */
    void r_cnjg(complex *, complex *);
    /* Local variables */
    integer i__, j, l;
    extern /* Subroutine */
    int cscal_(integer *, complex *, complex *, integer *), clarf_(char *, integer *, integer *, complex *, integer *, complex *, complex *, integer *, complex *), clacgv_(integer *, complex *, integer *), xerbla_(char *, integer *);
    /* -- LAPACK computational routine (version 3.4.2) -- */
    /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
    /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
    /* September 2012 */
    /* .. 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_("CUNGL2", &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)
            {
                i__3 = l + j * a_dim1;
                a[i__3].r = 0.f;
                a[i__3].i = 0.f; // , expr subst
                /* L10: */
            }
            if (j > *k && j <= *m)
            {
                i__2 = j + j * a_dim1;
                a[i__2].r = 1.f;
                a[i__2].i = 0.f; // , expr subst
            }
            /* L20: */
        }
    }
    for (i__ = *k;
            i__ >= 1;
            --i__)
    {
        /* Apply H(i)**H to A(i:m,i:n) from the right */
        if (i__ < *n)
        {
            i__1 = *n - i__;
            clacgv_(&i__1, &a[i__ + (i__ + 1) * a_dim1], lda);
            if (i__ < *m)
            {
                i__1 = i__ + i__ * a_dim1;
                a[i__1].r = 1.f;
                a[i__1].i = 0.f; // , expr subst
                i__1 = *m - i__;
                i__2 = *n - i__ + 1;
                r_cnjg(&q__1, &tau[i__]);
                clarf_("Right", &i__1, &i__2, &a[i__ + i__ * a_dim1], lda, & q__1, &a[i__ + 1 + i__ * a_dim1], lda, &work[1]);
            }
            i__1 = *n - i__;
            i__2 = i__;
            q__1.r = -tau[i__2].r;
            q__1.i = -tau[i__2].i; // , expr subst
            cscal_(&i__1, &q__1, &a[i__ + (i__ + 1) * a_dim1], lda);
            i__1 = *n - i__;
            clacgv_(&i__1, &a[i__ + (i__ + 1) * a_dim1], lda);
        }
        i__1 = i__ + i__ * a_dim1;
        r_cnjg(&q__2, &tau[i__]);
        q__1.r = 1.f - q__2.r;
        q__1.i = 0.f - q__2.i; // , expr subst
        a[i__1].r = q__1.r;
        a[i__1].i = q__1.i; // , expr subst
        /* Set A(i,1:i-1,i) to zero */
        i__1 = i__ - 1;
        for (l = 1;
                l <= i__1;
                ++l)
        {
            i__2 = i__ + l * a_dim1;
            a[i__2].r = 0.f;
            a[i__2].i = 0.f; // , expr subst
            /* L30: */
        }
        /* L40: */
    }
    return 0;
    /* End of CUNGL2 */
}

References complex::i, and complex::r.

Referenced by cunglq_fla().