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/* lapack/double/dlarf.f -- translated by f2c (version 20050501).
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
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "v3p_netlib.h"
/* Table of constant values */
static doublereal c_b4 = 1.;
static doublereal c_b5 = 0.;
static integer c__1 = 1;
/*< SUBROUTINE DLARF( SIDE, M, N, V, INCV, TAU, C, LDC, WORK ) >*/
/* Subroutine */ int dlarf_(char *side, integer *m, integer *n, doublereal *v,
integer *incv, doublereal *tau, doublereal *c__, integer *ldc,
doublereal *work, ftnlen side_len)
{
/* System generated locals */
integer c_dim1, c_offset;
doublereal d__1;
/* Local variables */
extern /* Subroutine */ int dger_(integer *, integer *, doublereal *,
doublereal *, integer *, doublereal *, integer *, doublereal *,
integer *);
extern logical lsame_(char *, char *, ftnlen, ftnlen);
extern /* Subroutine */ int dgemv_(char *, integer *, integer *,
doublereal *, doublereal *, integer *, doublereal *, integer *,
doublereal *, doublereal *, integer *, ftnlen);
(void)side_len;
/* -- LAPACK auxiliary routine (version 3.0) -- */
/* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
/* Courant Institute, Argonne National Lab, and Rice University */
/* February 29, 1992 */
/* .. Scalar Arguments .. */
/*< CHARACTER SIDE >*/
/*< INTEGER INCV, LDC, M, N >*/
/*< DOUBLE PRECISION TAU >*/
/* .. */
/* .. Array Arguments .. */
/*< DOUBLE PRECISION C( LDC, * ), V( * ), WORK( * ) >*/
/* .. */
/* Purpose */
/* ======= */
/* DLARF applies a real elementary reflector H to a real m by n matrix */
/* C, from either the left or the right. H is represented in the form */
/* H = I - tau * v * v' */
/* where tau is a real scalar and v is a real vector. */
/* If tau = 0, then H is taken to be the unit matrix. */
/* Arguments */
/* ========= */
/* SIDE (input) CHARACTER*1 */
/* = 'L': form H * C */
/* = 'R': form C * H */
/* M (input) INTEGER */
/* The number of rows of the matrix C. */
/* N (input) INTEGER */
/* The number of columns of the matrix C. */
/* V (input) DOUBLE PRECISION array, dimension */
/* (1 + (M-1)*abs(INCV)) if SIDE = 'L' */
/* or (1 + (N-1)*abs(INCV)) if SIDE = 'R' */
/* The vector v in the representation of H. V is not used if */
/* TAU = 0. */
/* INCV (input) INTEGER */
/* The increment between elements of v. INCV <> 0. */
/* TAU (input) DOUBLE PRECISION */
/* The value tau in the representation of H. */
/* C (input/output) DOUBLE PRECISION array, dimension (LDC,N) */
/* On entry, the m by n matrix C. */
/* On exit, C is overwritten by the matrix H * C if SIDE = 'L', */
/* or C * H if SIDE = 'R'. */
/* LDC (input) INTEGER */
/* The leading dimension of the array C. LDC >= max(1,M). */
/* WORK (workspace) DOUBLE PRECISION array, dimension */
/* (N) if SIDE = 'L' */
/* or (M) if SIDE = 'R' */
/* ===================================================================== */
/* .. Parameters .. */
/*< DOUBLE PRECISION ONE, ZERO >*/
/*< PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) >*/
/* .. */
/* .. External Subroutines .. */
/*< EXTERNAL DGEMV, DGER >*/
/* .. */
/* .. External Functions .. */
/*< LOGICAL LSAME >*/
/*< EXTERNAL LSAME >*/
/* .. */
/* .. Executable Statements .. */
/*< IF( LSAME( SIDE, 'L' ) ) THEN >*/
/* Parameter adjustments */
--v;
c_dim1 = *ldc;
c_offset = 1 + c_dim1;
c__ -= c_offset;
--work;
/* Function Body */
if (lsame_(side, "L", (ftnlen)1, (ftnlen)1)) {
/* Form H * C */
/*< IF( TAU.NE.ZERO ) THEN >*/
if (*tau != 0.) {
/* w := C' * v */
/*< >*/
dgemv_("Transpose", m, n, &c_b4, &c__[c_offset], ldc, &v[1], incv,
&c_b5, &work[1], &c__1, (ftnlen)9);
/* C := C - v * w' */
/*< CALL DGER( M, N, -TAU, V, INCV, WORK, 1, C, LDC ) >*/
d__1 = -(*tau);
dger_(m, n, &d__1, &v[1], incv, &work[1], &c__1, &c__[c_offset],
ldc);
/*< END IF >*/
}
/*< ELSE >*/
} else {
/* Form C * H */
/*< IF( TAU.NE.ZERO ) THEN >*/
if (*tau != 0.) {
/* w := C * v */
/*< >*/
dgemv_("No transpose", m, n, &c_b4, &c__[c_offset], ldc, &v[1],
incv, &c_b5, &work[1], &c__1, (ftnlen)12);
/* C := C - w * v' */
/*< CALL DGER( M, N, -TAU, WORK, 1, V, INCV, C, LDC ) >*/
d__1 = -(*tau);
dger_(m, n, &d__1, &work[1], &c__1, &v[1], incv, &c__[c_offset],
ldc);
/*< END IF >*/
}
/*< END IF >*/
}
/*< RETURN >*/
return 0;
/* End of DLARF */
/*< END >*/
} /* dlarf_ */
#ifdef __cplusplus
}
#endif
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