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/* dlarzb.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 integer c__1 = 1;
static doublereal c_b13 = 1.;
static doublereal c_b23 = -1.;
/* Subroutine */ int dlarzb_(char *side, char *trans, char *direct, char *
storev, integer *m, integer *n, integer *k, integer *l, doublereal *v,
integer *ldv, doublereal *t, integer *ldt, doublereal *c__, integer *
ldc, doublereal *work, integer *ldwork)
{
/* System generated locals */
integer c_dim1, c_offset, t_dim1, t_offset, v_dim1, v_offset, work_dim1,
work_offset, i__1, i__2;
/* Local variables */
integer i__, j, info;
extern /* Subroutine */ int dgemm_(char *, char *, integer *, integer *,
integer *, doublereal *, doublereal *, integer *, doublereal *,
integer *, doublereal *, doublereal *, integer *);
extern logical lsame_(char *, char *);
extern /* Subroutine */ int dcopy_(integer *, doublereal *, integer *,
doublereal *, integer *), dtrmm_(char *, char *, char *, char *,
integer *, integer *, doublereal *, doublereal *, integer *,
doublereal *, integer *), xerbla_(
char *, integer *);
char transt[1];
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DLARZB applies a real block reflector H or its transpose H**T to */
/* a real distributed M-by-N C from the left or the right. */
/* Currently, only STOREV = 'R' and DIRECT = 'B' are supported. */
/* Arguments */
/* ========= */
/* SIDE (input) CHARACTER*1 */
/* = 'L': apply H or H' from the Left */
/* = 'R': apply H or H' from the Right */
/* TRANS (input) CHARACTER*1 */
/* = 'N': apply H (No transpose) */
/* = 'C': apply H' (Transpose) */
/* DIRECT (input) CHARACTER*1 */
/* Indicates how H is formed from a product of elementary */
/* reflectors */
/* = 'F': H = H(1) H(2) . . . H(k) (Forward, not supported yet) */
/* = 'B': H = H(k) . . . H(2) H(1) (Backward) */
/* STOREV (input) CHARACTER*1 */
/* Indicates how the vectors which define the elementary */
/* reflectors are stored: */
/* = 'C': Columnwise (not supported yet) */
/* = 'R': Rowwise */
/* M (input) INTEGER */
/* The number of rows of the matrix C. */
/* N (input) INTEGER */
/* The number of columns of the matrix C. */
/* K (input) INTEGER */
/* The order of the matrix T (= the number of elementary */
/* reflectors whose product defines the block reflector). */
/* L (input) INTEGER */
/* The number of columns of the matrix V containing the */
/* meaningful part of the Householder reflectors. */
/* If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0. */
/* V (input) DOUBLE PRECISION array, dimension (LDV,NV). */
/* If STOREV = 'C', NV = K; if STOREV = 'R', NV = L. */
/* LDV (input) INTEGER */
/* The leading dimension of the array V. */
/* If STOREV = 'C', LDV >= L; if STOREV = 'R', LDV >= K. */
/* T (input) DOUBLE PRECISION array, dimension (LDT,K) */
/* The triangular K-by-K matrix T in the representation of the */
/* block reflector. */
/* LDT (input) INTEGER */
/* The leading dimension of the array T. LDT >= K. */
/* C (input/output) DOUBLE PRECISION array, dimension (LDC,N) */
/* On entry, the M-by-N matrix C. */
/* On exit, C is overwritten by H*C or H'*C or C*H or C*H'. */
/* LDC (input) INTEGER */
/* The leading dimension of the array C. LDC >= max(1,M). */
/* WORK (workspace) DOUBLE PRECISION array, dimension (LDWORK,K) */
/* LDWORK (input) INTEGER */
/* The leading dimension of the array WORK. */
/* If SIDE = 'L', LDWORK >= max(1,N); */
/* if SIDE = 'R', LDWORK >= max(1,M). */
/* Further Details */
/* =============== */
/* Based on contributions by */
/* A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Executable Statements .. */
/* Quick return if possible */
/* Parameter adjustments */
v_dim1 = *ldv;
v_offset = 1 + v_dim1;
v -= v_offset;
t_dim1 = *ldt;
t_offset = 1 + t_dim1;
t -= t_offset;
c_dim1 = *ldc;
c_offset = 1 + c_dim1;
c__ -= c_offset;
work_dim1 = *ldwork;
work_offset = 1 + work_dim1;
work -= work_offset;
/* Function Body */
if (*m <= 0 || *n <= 0) {
return 0;
}
/* Check for currently supported options */
info = 0;
if (! lsame_(direct, "B")) {
info = -3;
} else if (! lsame_(storev, "R")) {
info = -4;
}
if (info != 0) {
i__1 = -info;
xerbla_("DLARZB", &i__1);
return 0;
}
if (lsame_(trans, "N")) {
*(unsigned char *)transt = 'T';
} else {
*(unsigned char *)transt = 'N';
}
if (lsame_(side, "L")) {
/* Form H * C or H' * C */
/* W( 1:n, 1:k ) = C( 1:k, 1:n )' */
i__1 = *k;
for (j = 1; j <= i__1; ++j) {
dcopy_(n, &c__[j + c_dim1], ldc, &work[j * work_dim1 + 1], &c__1);
/* L10: */
}
/* W( 1:n, 1:k ) = W( 1:n, 1:k ) + ... */
/* C( m-l+1:m, 1:n )' * V( 1:k, 1:l )' */
if (*l > 0) {
dgemm_("Transpose", "Transpose", n, k, l, &c_b13, &c__[*m - *l +
1 + c_dim1], ldc, &v[v_offset], ldv, &c_b13, &work[
work_offset], ldwork);
}
/* W( 1:n, 1:k ) = W( 1:n, 1:k ) * T' or W( 1:m, 1:k ) * T */
dtrmm_("Right", "Lower", transt, "Non-unit", n, k, &c_b13, &t[
t_offset], ldt, &work[work_offset], ldwork);
/* C( 1:k, 1:n ) = C( 1:k, 1:n ) - W( 1:n, 1:k )' */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *k;
for (i__ = 1; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] -= work[j + i__ * work_dim1];
/* L20: */
}
/* L30: */
}
/* C( m-l+1:m, 1:n ) = C( m-l+1:m, 1:n ) - ... */
/* V( 1:k, 1:l )' * W( 1:n, 1:k )' */
if (*l > 0) {
dgemm_("Transpose", "Transpose", l, n, k, &c_b23, &v[v_offset],
ldv, &work[work_offset], ldwork, &c_b13, &c__[*m - *l + 1
+ c_dim1], ldc);
}
} else if (lsame_(side, "R")) {
/* Form C * H or C * H' */
/* W( 1:m, 1:k ) = C( 1:m, 1:k ) */
i__1 = *k;
for (j = 1; j <= i__1; ++j) {
dcopy_(m, &c__[j * c_dim1 + 1], &c__1, &work[j * work_dim1 + 1], &
c__1);
/* L40: */
}
/* W( 1:m, 1:k ) = W( 1:m, 1:k ) + ... */
/* C( 1:m, n-l+1:n ) * V( 1:k, 1:l )' */
if (*l > 0) {
dgemm_("No transpose", "Transpose", m, k, l, &c_b13, &c__[(*n - *
l + 1) * c_dim1 + 1], ldc, &v[v_offset], ldv, &c_b13, &
work[work_offset], ldwork);
}
/* W( 1:m, 1:k ) = W( 1:m, 1:k ) * T or W( 1:m, 1:k ) * T' */
dtrmm_("Right", "Lower", trans, "Non-unit", m, k, &c_b13, &t[t_offset]
, ldt, &work[work_offset], ldwork);
/* C( 1:m, 1:k ) = C( 1:m, 1:k ) - W( 1:m, 1:k ) */
i__1 = *k;
for (j = 1; j <= i__1; ++j) {
i__2 = *m;
for (i__ = 1; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] -= work[i__ + j * work_dim1];
/* L50: */
}
/* L60: */
}
/* C( 1:m, n-l+1:n ) = C( 1:m, n-l+1:n ) - ... */
/* W( 1:m, 1:k ) * V( 1:k, 1:l ) */
if (*l > 0) {
dgemm_("No transpose", "No transpose", m, l, k, &c_b23, &work[
work_offset], ldwork, &v[v_offset], ldv, &c_b13, &c__[(*n
- *l + 1) * c_dim1 + 1], ldc);
}
}
return 0;
/* End of DLARZB */
} /* dlarzb_ */
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