sopgtr.c File Reference

(r)

Functions
int	sopgtr_ (char *uplo, integer *n, real *ap, real *tau, real *q, integer *ldq, real *work, integer *info)

Function Documentation

sopgtr_()

int sopgtr_	(	char *	uplo,
		integer *	n,
		real *	ap,
		real *	tau,
		real *	q,
		integer *	ldq,
		real *	work,
		integer *	info
	)

{
    /* System generated locals */
    integer q_dim1, q_offset, i__1, i__2, i__3;
    /* Local variables */
    integer i__, j, ij;
    extern logical lsame_(char *, char *);
    integer iinfo;
    logical upper;
    extern /* Subroutine */
    int sorg2l_(integer *, integer *, integer *, real *, integer *, real *, real *, integer *), sorg2r_fla(integer *, integer *, integer *, real *, integer *, real *, real *, integer * ), 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 Functions .. */
    /* .. */
    /* .. External Subroutines .. */
    /* .. */
    /* .. Intrinsic Functions .. */
    /* .. */
    /* .. Executable Statements .. */
    /* Test the input arguments */
    /* Parameter adjustments */
    --ap;
    --tau;
    q_dim1 = *ldq;
    q_offset = 1 + q_dim1;
    q -= q_offset;
    --work;
    /* Function Body */
    *info = 0;
    upper = lsame_(uplo, "U");
    if (! upper && ! lsame_(uplo, "L"))
    {
        *info = -1;
    }
    else if (*n < 0)
    {
        *info = -2;
    }
    else if (*ldq < max(1,*n))
    {
        *info = -6;
    }
    if (*info != 0)
    {
        i__1 = -(*info);
        xerbla_("SOPGTR", &i__1);
        return 0;
    }
    /* Quick return if possible */
    if (*n == 0)
    {
        return 0;
    }
    if (upper)
    {
        /* Q was determined by a call to SSPTRD with UPLO = 'U' */
        /* Unpack the vectors which define the elementary reflectors and */
        /* set the last row and column of Q equal to those of the unit */
        /* matrix */
        ij = 2;
        i__1 = *n - 1;
        for (j = 1;
                j <= i__1;
                ++j)
        {
            i__2 = j - 1;
            for (i__ = 1;
                    i__ <= i__2;
                    ++i__)
            {
                q[i__ + j * q_dim1] = ap[ij];
                ++ij;
                /* L10: */
            }
            ij += 2;
            q[*n + j * q_dim1] = 0.f;
            /* L20: */
        }
        i__1 = *n - 1;
        for (i__ = 1;
                i__ <= i__1;
                ++i__)
        {
            q[i__ + *n * q_dim1] = 0.f;
            /* L30: */
        }
        q[*n + *n * q_dim1] = 1.f;
        /* Generate Q(1:n-1,1:n-1) */
        i__1 = *n - 1;
        i__2 = *n - 1;
        i__3 = *n - 1;
        sorg2l_(&i__1, &i__2, &i__3, &q[q_offset], ldq, &tau[1], &work[1], & iinfo);
    }
    else
    {
        /* Q was determined by a call to SSPTRD with UPLO = 'L'. */
        /* Unpack the vectors which define the elementary reflectors and */
        /* set the first row and column of Q equal to those of the unit */
        /* matrix */
        q[q_dim1 + 1] = 1.f;
        i__1 = *n;
        for (i__ = 2;
                i__ <= i__1;
                ++i__)
        {
            q[i__ + q_dim1] = 0.f;
            /* L40: */
        }
        ij = 3;
        i__1 = *n;
        for (j = 2;
                j <= i__1;
                ++j)
        {
            q[j * q_dim1 + 1] = 0.f;
            i__2 = *n;
            for (i__ = j + 1;
                    i__ <= i__2;
                    ++i__)
            {
                q[i__ + j * q_dim1] = ap[ij];
                ++ij;
                /* L50: */
            }
            ij += 2;
            /* L60: */
        }
        if (*n > 1)
        {
            /* Generate Q(2:n,2:n) */
            i__1 = *n - 1;
            i__2 = *n - 1;
            i__3 = *n - 1;
            sorg2r_fla(&i__1, &i__2, &i__3, &q[(q_dim1 << 1) + 2], ldq, &tau[1], &work[1], &iinfo);
        }
    }
    return 0;
    /* End of SOPGTR */
}

References i, and sorg2r_fla().