cgbbrd.c

/* cgbbrd.f -- translated by f2c (version 20061008).
   You must link the resulting object file with libf2c:
	on Microsoft Windows system, link with libf2c.lib;
	on Linux or Unix systems, link with .../path/to/libf2c.a -lm
	or, if you install libf2c.a in a standard place, with -lf2c -lm
	-- in that order, at the end of the command line, as in
		cc *.o -lf2c -lm
	Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,

		http://www.netlib.org/f2c/libf2c.zip
*/

#include "f2c.h"
#include "blaswrap.h"

/* Table of constant values */

static complex c_b1 = {0.f,0.f};
static complex c_b2 = {1.f,0.f};
static integer c__1 = 1;

/* Subroutine */ int cgbbrd_(char *vect, integer *m, integer *n, integer *ncc, 
	 integer *kl, integer *ku, complex *ab, integer *ldab, real *d__, 
	real *e, complex *q, integer *ldq, complex *pt, integer *ldpt, 
	complex *c__, integer *ldc, complex *work, real *rwork, integer *info)
{
    /* System generated locals */
    integer ab_dim1, ab_offset, c_dim1, c_offset, pt_dim1, pt_offset, q_dim1, 
	    q_offset, i__1, i__2, i__3, i__4, i__5, i__6, i__7;
    complex q__1, q__2, q__3;

    /* Builtin functions */
    void r_cnjg(complex *, complex *);
    double c_abs(complex *);

    /* Local variables */
    integer i__, j, l;
    complex t;
    integer j1, j2, kb;
    complex ra, rb;
    real rc;
    integer kk, ml, nr, mu;
    complex rs;
    integer kb1, ml0, mu0, klm, kun, nrt, klu1, inca;
    real abst;
    extern /* Subroutine */ int crot_(integer *, complex *, integer *, 
	    complex *, integer *, real *, complex *), cscal_(integer *, 
	    complex *, complex *, integer *);
    extern logical lsame_(char *, char *);
    logical wantb, wantc;
    integer minmn;
    logical wantq;
    extern /* Subroutine */ int claset_(char *, integer *, integer *, complex 
	    *, complex *, complex *, integer *), clartg_(complex *, 
	    complex *, real *, complex *, complex *), xerbla_(char *, integer 
	    *), clargv_(integer *, complex *, integer *, complex *, 
	    integer *, real *, integer *), clartv_(integer *, complex *, 
	    integer *, complex *, integer *, real *, complex *, integer *);
    logical wantpt;


/*  -- LAPACK routine (version 3.2) -- */
/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/*     November 2006 */

/*     .. Scalar Arguments .. */
/*     .. */
/*     .. Array Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */

/*  CGBBRD reduces a complex general m-by-n band matrix A to real upper */
/*  bidiagonal form B by a unitary transformation: Q' * A * P = B. */

/*  The routine computes B, and optionally forms Q or P', or computes */
/*  Q'*C for a given matrix C. */

/*  Arguments */
/*  ========= */

/*  VECT    (input) CHARACTER*1 */
/*          Specifies whether or not the matrices Q and P' are to be */
/*          formed. */
/*          = 'N': do not form Q or P'; */
/*          = 'Q': form Q only; */
/*          = 'P': form P' only; */
/*          = 'B': form both. */

/*  M       (input) INTEGER */
/*          The number of rows of the matrix A.  M >= 0. */

/*  N       (input) INTEGER */
/*          The number of columns of the matrix A.  N >= 0. */

/*  NCC     (input) INTEGER */
/*          The number of columns of the matrix C.  NCC >= 0. */

/*  KL      (input) INTEGER */
/*          The number of subdiagonals of the matrix A. KL >= 0. */

/*  KU      (input) INTEGER */
/*          The number of superdiagonals of the matrix A. KU >= 0. */

/*  AB      (input/output) COMPLEX array, dimension (LDAB,N) */
/*          On entry, the m-by-n band matrix A, stored in rows 1 to */
/*          KL+KU+1. The j-th column of A is stored in the j-th column of */
/*          the array AB as follows: */
/*          AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl). */
/*          On exit, A is overwritten by values generated during the */
/*          reduction. */

/*  LDAB    (input) INTEGER */
/*          The leading dimension of the array A. LDAB >= KL+KU+1. */

/*  D       (output) REAL array, dimension (min(M,N)) */
/*          The diagonal elements of the bidiagonal matrix B. */

/*  E       (output) REAL array, dimension (min(M,N)-1) */
/*          The superdiagonal elements of the bidiagonal matrix B. */

/*  Q       (output) COMPLEX array, dimension (LDQ,M) */
/*          If VECT = 'Q' or 'B', the m-by-m unitary matrix Q. */
/*          If VECT = 'N' or 'P', the array Q is not referenced. */

/*  LDQ     (input) INTEGER */
/*          The leading dimension of the array Q. */
/*          LDQ >= max(1,M) if VECT = 'Q' or 'B'; LDQ >= 1 otherwise. */

/*  PT      (output) COMPLEX array, dimension (LDPT,N) */
/*          If VECT = 'P' or 'B', the n-by-n unitary matrix P'. */
/*          If VECT = 'N' or 'Q', the array PT is not referenced. */

/*  LDPT    (input) INTEGER */
/*          The leading dimension of the array PT. */
/*          LDPT >= max(1,N) if VECT = 'P' or 'B'; LDPT >= 1 otherwise. */

/*  C       (input/output) COMPLEX array, dimension (LDC,NCC) */
/*          On entry, an m-by-ncc matrix C. */
/*          On exit, C is overwritten by Q'*C. */
/*          C is not referenced if NCC = 0. */

/*  LDC     (input) INTEGER */
/*          The leading dimension of the array C. */
/*          LDC >= max(1,M) if NCC > 0; LDC >= 1 if NCC = 0. */

/*  WORK    (workspace) COMPLEX array, dimension (max(M,N)) */

/*  RWORK   (workspace) REAL array, dimension (max(M,N)) */

/*  INFO    (output) INTEGER */
/*          = 0:  successful exit. */
/*          < 0:  if INFO = -i, the i-th argument had an illegal value. */

/*  ===================================================================== */

/*     .. Parameters .. */
/*     .. */
/*     .. Local Scalars .. */
/*     .. */
/*     .. External Subroutines .. */
/*     .. */
/*     .. Intrinsic Functions .. */
/*     .. */
/*     .. External Functions .. */
/*     .. */
/*     .. Executable Statements .. */

/*     Test the input parameters */

    /* Parameter adjustments */
    ab_dim1 = *ldab;
    ab_offset = 1 + ab_dim1;
    ab -= ab_offset;
    --d__;
    --e;
    q_dim1 = *ldq;
    q_offset = 1 + q_dim1;
    q -= q_offset;
    pt_dim1 = *ldpt;
    pt_offset = 1 + pt_dim1;
    pt -= pt_offset;
    c_dim1 = *ldc;
    c_offset = 1 + c_dim1;
    c__ -= c_offset;
    --work;
    --rwork;

    /* Function Body */
    wantb = lsame_(vect, "B");
    wantq = lsame_(vect, "Q") || wantb;
    wantpt = lsame_(vect, "P") || wantb;
    wantc = *ncc > 0;
    klu1 = *kl + *ku + 1;
    *info = 0;
    if (! wantq && ! wantpt && ! lsame_(vect, "N")) {
	*info = -1;
    } else if (*m < 0) {
	*info = -2;
    } else if (*n < 0) {
	*info = -3;
    } else if (*ncc < 0) {
	*info = -4;
    } else if (*kl < 0) {
	*info = -5;
    } else if (*ku < 0) {
	*info = -6;
    } else if (*ldab < klu1) {
	*info = -8;
    } else if (*ldq < 1 || wantq && *ldq < max(1,*m)) {
	*info = -12;
    } else if (*ldpt < 1 || wantpt && *ldpt < max(1,*n)) {
	*info = -14;
    } else if (*ldc < 1 || wantc && *ldc < max(1,*m)) {
	*info = -16;
    }
    if (*info != 0) {
	i__1 = -(*info);
	xerbla_("CGBBRD", &i__1);
	return 0;
    }

/*     Initialize Q and P' to the unit matrix, if needed */

    if (wantq) {
	claset_("Full", m, m, &c_b1, &c_b2, &q[q_offset], ldq);
    }
    if (wantpt) {
	claset_("Full", n, n, &c_b1, &c_b2, &pt[pt_offset], ldpt);
    }

/*     Quick return if possible. */

    if (*m == 0 || *n == 0) {
	return 0;
    }

    minmn = min(*m,*n);

    if (*kl + *ku > 1) {

/*        Reduce to upper bidiagonal form if KU > 0; if KU = 0, reduce */
/*        first to lower bidiagonal form and then transform to upper */
/*        bidiagonal */

	if (*ku > 0) {
	    ml0 = 1;
	    mu0 = 2;
	} else {
	    ml0 = 2;
	    mu0 = 1;
	}

/*        Wherever possible, plane rotations are generated and applied in */
/*        vector operations of length NR over the index set J1:J2:KLU1. */

/*        The complex sines of the plane rotations are stored in WORK, */
/*        and the real cosines in RWORK. */

/* Computing MIN */
	i__1 = *m - 1;
	klm = min(i__1,*kl);
/* Computing MIN */
	i__1 = *n - 1;
	kun = min(i__1,*ku);
	kb = klm + kun;
	kb1 = kb + 1;
	inca = kb1 * *ldab;
	nr = 0;
	j1 = klm + 2;
	j2 = 1 - kun;

	i__1 = minmn;
	for (i__ = 1; i__ <= i__1; ++i__) {

/*           Reduce i-th column and i-th row of matrix to bidiagonal form */

	    ml = klm + 1;
	    mu = kun + 1;
	    i__2 = kb;
	    for (kk = 1; kk <= i__2; ++kk) {
		j1 += kb;
		j2 += kb;

/*              generate plane rotations to annihilate nonzero elements */
/*              which have been created below the band */

		if (nr > 0) {
		    clargv_(&nr, &ab[klu1 + (j1 - klm - 1) * ab_dim1], &inca, 
			    &work[j1], &kb1, &rwork[j1], &kb1);
		}

/*              apply plane rotations from the left */

		i__3 = kb;
		for (l = 1; l <= i__3; ++l) {
		    if (j2 - klm + l - 1 > *n) {
			nrt = nr - 1;
		    } else {
			nrt = nr;
		    }
		    if (nrt > 0) {
			clartv_(&nrt, &ab[klu1 - l + (j1 - klm + l - 1) * 
				ab_dim1], &inca, &ab[klu1 - l + 1 + (j1 - klm 
				+ l - 1) * ab_dim1], &inca, &rwork[j1], &work[
				j1], &kb1);
		    }
/* L10: */
		}

		if (ml > ml0) {
		    if (ml <= *m - i__ + 1) {

/*                    generate plane rotation to annihilate a(i+ml-1,i) */
/*                    within the band, and apply rotation from the left */

			clartg_(&ab[*ku + ml - 1 + i__ * ab_dim1], &ab[*ku + 
				ml + i__ * ab_dim1], &rwork[i__ + ml - 1], &
				work[i__ + ml - 1], &ra);
			i__3 = *ku + ml - 1 + i__ * ab_dim1;
			ab[i__3].r = ra.r, ab[i__3].i = ra.i;
			if (i__ < *n) {
/* Computing MIN */
			    i__4 = *ku + ml - 2, i__5 = *n - i__;
			    i__3 = min(i__4,i__5);
			    i__6 = *ldab - 1;
			    i__7 = *ldab - 1;
			    crot_(&i__3, &ab[*ku + ml - 2 + (i__ + 1) * 
				    ab_dim1], &i__6, &ab[*ku + ml - 1 + (i__ 
				    + 1) * ab_dim1], &i__7, &rwork[i__ + ml - 
				    1], &work[i__ + ml - 1]);
			}
		    }
		    ++nr;
		    j1 -= kb1;
		}

		if (wantq) {

/*                 accumulate product of plane rotations in Q */

		    i__3 = j2;
		    i__4 = kb1;
		    for (j = j1; i__4 < 0 ? j >= i__3 : j <= i__3; j += i__4) 
			    {
			r_cnjg(&q__1, &work[j]);
			crot_(m, &q[(j - 1) * q_dim1 + 1], &c__1, &q[j * 
				q_dim1 + 1], &c__1, &rwork[j], &q__1);
/* L20: */
		    }
		}

		if (wantc) {

/*                 apply plane rotations to C */

		    i__4 = j2;
		    i__3 = kb1;
		    for (j = j1; i__3 < 0 ? j >= i__4 : j <= i__4; j += i__3) 
			    {
			crot_(ncc, &c__[j - 1 + c_dim1], ldc, &c__[j + c_dim1]
, ldc, &rwork[j], &work[j]);
/* L30: */
		    }
		}

		if (j2 + kun > *n) {

/*                 adjust J2 to keep within the bounds of the matrix */

		    --nr;
		    j2 -= kb1;
		}

		i__3 = j2;
		i__4 = kb1;
		for (j = j1; i__4 < 0 ? j >= i__3 : j <= i__3; j += i__4) {

/*                 create nonzero element a(j-1,j+ku) above the band */
/*                 and store it in WORK(n+1:2*n) */

		    i__5 = j + kun;
		    i__6 = j;
		    i__7 = (j + kun) * ab_dim1 + 1;
		    q__1.r = work[i__6].r * ab[i__7].r - work[i__6].i * ab[
			    i__7].i, q__1.i = work[i__6].r * ab[i__7].i + 
			    work[i__6].i * ab[i__7].r;
		    work[i__5].r = q__1.r, work[i__5].i = q__1.i;
		    i__5 = (j + kun) * ab_dim1 + 1;
		    i__6 = j;
		    i__7 = (j + kun) * ab_dim1 + 1;
		    q__1.r = rwork[i__6] * ab[i__7].r, q__1.i = rwork[i__6] * 
			    ab[i__7].i;
		    ab[i__5].r = q__1.r, ab[i__5].i = q__1.i;
/* L40: */
		}

/*              generate plane rotations to annihilate nonzero elements */
/*              which have been generated above the band */

		if (nr > 0) {
		    clargv_(&nr, &ab[(j1 + kun - 1) * ab_dim1 + 1], &inca, &
			    work[j1 + kun], &kb1, &rwork[j1 + kun], &kb1);
		}

/*              apply plane rotations from the right */

		i__4 = kb;
		for (l = 1; l <= i__4; ++l) {
		    if (j2 + l - 1 > *m) {
			nrt = nr - 1;
		    } else {
			nrt = nr;
		    }
		    if (nrt > 0) {
			clartv_(&nrt, &ab[l + 1 + (j1 + kun - 1) * ab_dim1], &
				inca, &ab[l + (j1 + kun) * ab_dim1], &inca, &
				rwork[j1 + kun], &work[j1 + kun], &kb1);
		    }
/* L50: */
		}

		if (ml == ml0 && mu > mu0) {
		    if (mu <= *n - i__ + 1) {

/*                    generate plane rotation to annihilate a(i,i+mu-1) */
/*                    within the band, and apply rotation from the right */

			clartg_(&ab[*ku - mu + 3 + (i__ + mu - 2) * ab_dim1], 
				&ab[*ku - mu + 2 + (i__ + mu - 1) * ab_dim1], 
				&rwork[i__ + mu - 1], &work[i__ + mu - 1], &
				ra);
			i__4 = *ku - mu + 3 + (i__ + mu - 2) * ab_dim1;
			ab[i__4].r = ra.r, ab[i__4].i = ra.i;
/* Computing MIN */
			i__3 = *kl + mu - 2, i__5 = *m - i__;
			i__4 = min(i__3,i__5);
			crot_(&i__4, &ab[*ku - mu + 4 + (i__ + mu - 2) * 
				ab_dim1], &c__1, &ab[*ku - mu + 3 + (i__ + mu 
				- 1) * ab_dim1], &c__1, &rwork[i__ + mu - 1], 
				&work[i__ + mu - 1]);
		    }
		    ++nr;
		    j1 -= kb1;
		}

		if (wantpt) {

/*                 accumulate product of plane rotations in P' */

		    i__4 = j2;
		    i__3 = kb1;
		    for (j = j1; i__3 < 0 ? j >= i__4 : j <= i__4; j += i__3) 
			    {
			r_cnjg(&q__1, &work[j + kun]);
			crot_(n, &pt[j + kun - 1 + pt_dim1], ldpt, &pt[j + 
				kun + pt_dim1], ldpt, &rwork[j + kun], &q__1);
/* L60: */
		    }
		}

		if (j2 + kb > *m) {

/*                 adjust J2 to keep within the bounds of the matrix */

		    --nr;
		    j2 -= kb1;
		}

		i__3 = j2;
		i__4 = kb1;
		for (j = j1; i__4 < 0 ? j >= i__3 : j <= i__3; j += i__4) {

/*                 create nonzero element a(j+kl+ku,j+ku-1) below the */
/*                 band and store it in WORK(1:n) */

		    i__5 = j + kb;
		    i__6 = j + kun;
		    i__7 = klu1 + (j + kun) * ab_dim1;
		    q__1.r = work[i__6].r * ab[i__7].r - work[i__6].i * ab[
			    i__7].i, q__1.i = work[i__6].r * ab[i__7].i + 
			    work[i__6].i * ab[i__7].r;
		    work[i__5].r = q__1.r, work[i__5].i = q__1.i;
		    i__5 = klu1 + (j + kun) * ab_dim1;
		    i__6 = j + kun;
		    i__7 = klu1 + (j + kun) * ab_dim1;
		    q__1.r = rwork[i__6] * ab[i__7].r, q__1.i = rwork[i__6] * 
			    ab[i__7].i;
		    ab[i__5].r = q__1.r, ab[i__5].i = q__1.i;
/* L70: */
		}

		if (ml > ml0) {
		    --ml;
		} else {
		    --mu;
		}
/* L80: */
	    }
/* L90: */
	}
    }

    if (*ku == 0 && *kl > 0) {

/*        A has been reduced to complex lower bidiagonal form */

/*        Transform lower bidiagonal form to upper bidiagonal by applying */
/*        plane rotations from the left, overwriting superdiagonal */
/*        elements on subdiagonal elements */

/* Computing MIN */
	i__2 = *m - 1;
	i__1 = min(i__2,*n);
	for (i__ = 1; i__ <= i__1; ++i__) {
	    clartg_(&ab[i__ * ab_dim1 + 1], &ab[i__ * ab_dim1 + 2], &rc, &rs, 
		    &ra);
	    i__2 = i__ * ab_dim1 + 1;
	    ab[i__2].r = ra.r, ab[i__2].i = ra.i;
	    if (i__ < *n) {
		i__2 = i__ * ab_dim1 + 2;
		i__4 = (i__ + 1) * ab_dim1 + 1;
		q__1.r = rs.r * ab[i__4].r - rs.i * ab[i__4].i, q__1.i = rs.r 
			* ab[i__4].i + rs.i * ab[i__4].r;
		ab[i__2].r = q__1.r, ab[i__2].i = q__1.i;
		i__2 = (i__ + 1) * ab_dim1 + 1;
		i__4 = (i__ + 1) * ab_dim1 + 1;
		q__1.r = rc * ab[i__4].r, q__1.i = rc * ab[i__4].i;
		ab[i__2].r = q__1.r, ab[i__2].i = q__1.i;
	    }
	    if (wantq) {
		r_cnjg(&q__1, &rs);
		crot_(m, &q[i__ * q_dim1 + 1], &c__1, &q[(i__ + 1) * q_dim1 + 
			1], &c__1, &rc, &q__1);
	    }
	    if (wantc) {
		crot_(ncc, &c__[i__ + c_dim1], ldc, &c__[i__ + 1 + c_dim1], 
			ldc, &rc, &rs);
	    }
/* L100: */
	}
    } else {

/*        A has been reduced to complex upper bidiagonal form or is */
/*        diagonal */

	if (*ku > 0 && *m < *n) {

/*           Annihilate a(m,m+1) by applying plane rotations from the */
/*           right */

	    i__1 = *ku + (*m + 1) * ab_dim1;
	    rb.r = ab[i__1].r, rb.i = ab[i__1].i;
	    for (i__ = *m; i__ >= 1; --i__) {
		clartg_(&ab[*ku + 1 + i__ * ab_dim1], &rb, &rc, &rs, &ra);
		i__1 = *ku + 1 + i__ * ab_dim1;
		ab[i__1].r = ra.r, ab[i__1].i = ra.i;
		if (i__ > 1) {
		    r_cnjg(&q__3, &rs);
		    q__2.r = -q__3.r, q__2.i = -q__3.i;
		    i__1 = *ku + i__ * ab_dim1;
		    q__1.r = q__2.r * ab[i__1].r - q__2.i * ab[i__1].i, 
			    q__1.i = q__2.r * ab[i__1].i + q__2.i * ab[i__1]
			    .r;
		    rb.r = q__1.r, rb.i = q__1.i;
		    i__1 = *ku + i__ * ab_dim1;
		    i__2 = *ku + i__ * ab_dim1;
		    q__1.r = rc * ab[i__2].r, q__1.i = rc * ab[i__2].i;
		    ab[i__1].r = q__1.r, ab[i__1].i = q__1.i;
		}
		if (wantpt) {
		    r_cnjg(&q__1, &rs);
		    crot_(n, &pt[i__ + pt_dim1], ldpt, &pt[*m + 1 + pt_dim1], 
			    ldpt, &rc, &q__1);
		}
/* L110: */
	    }
	}
    }

/*     Make diagonal and superdiagonal elements real, storing them in D */
/*     and E */

    i__1 = *ku + 1 + ab_dim1;
    t.r = ab[i__1].r, t.i = ab[i__1].i;
    i__1 = minmn;
    for (i__ = 1; i__ <= i__1; ++i__) {
	abst = c_abs(&t);
	d__[i__] = abst;
	if (abst != 0.f) {
	    q__1.r = t.r / abst, q__1.i = t.i / abst;
	    t.r = q__1.r, t.i = q__1.i;
	} else {
	    t.r = 1.f, t.i = 0.f;
	}
	if (wantq) {
	    cscal_(m, &t, &q[i__ * q_dim1 + 1], &c__1);
	}
	if (wantc) {
	    r_cnjg(&q__1, &t);
	    cscal_(ncc, &q__1, &c__[i__ + c_dim1], ldc);
	}
	if (i__ < minmn) {
	    if (*ku == 0 && *kl == 0) {
		e[i__] = 0.f;
		i__2 = (i__ + 1) * ab_dim1 + 1;
		t.r = ab[i__2].r, t.i = ab[i__2].i;
	    } else {
		if (*ku == 0) {
		    i__2 = i__ * ab_dim1 + 2;
		    r_cnjg(&q__2, &t);
		    q__1.r = ab[i__2].r * q__2.r - ab[i__2].i * q__2.i, 
			    q__1.i = ab[i__2].r * q__2.i + ab[i__2].i * 
			    q__2.r;
		    t.r = q__1.r, t.i = q__1.i;
		} else {
		    i__2 = *ku + (i__ + 1) * ab_dim1;
		    r_cnjg(&q__2, &t);
		    q__1.r = ab[i__2].r * q__2.r - ab[i__2].i * q__2.i, 
			    q__1.i = ab[i__2].r * q__2.i + ab[i__2].i * 
			    q__2.r;
		    t.r = q__1.r, t.i = q__1.i;
		}
		abst = c_abs(&t);
		e[i__] = abst;
		if (abst != 0.f) {
		    q__1.r = t.r / abst, q__1.i = t.i / abst;
		    t.r = q__1.r, t.i = q__1.i;
		} else {
		    t.r = 1.f, t.i = 0.f;
		}
		if (wantpt) {
		    cscal_(n, &t, &pt[i__ + 1 + pt_dim1], ldpt);
		}
		i__2 = *ku + 1 + (i__ + 1) * ab_dim1;
		r_cnjg(&q__2, &t);
		q__1.r = ab[i__2].r * q__2.r - ab[i__2].i * q__2.i, q__1.i = 
			ab[i__2].r * q__2.i + ab[i__2].i * q__2.r;
		t.r = q__1.r, t.i = q__1.i;
	    }
	}
/* L120: */
    }
    return 0;

/*     End of CGBBRD */

} /* cgbbrd_ */