hypre/lapack/dorg2l.c
falgout e3181f26b1 Added 64 bit feature using HYPRE_Int (see tracker [issue489] for details).
Changed MPI routines to hypre_MPI routines.
Added hypre_printf, etc. routines.
Added AUTOTEST tests to look for 'int' and 'MPI_' calls.
Added a new approach for the Fortran interface (not implemented everywhere yet).
2010-12-20 19:27:44 +00:00

156 lines
4.0 KiB
C

#include "../blas/hypre_blas.h"
#include "hypre_lapack.h"
#include "f2c.h"
/* Subroutine */ HYPRE_Int dorg2l_(integer *m, integer *n, integer *k, doublereal *
a, integer *lda, doublereal *tau, doublereal *work, integer *info)
{
/* -- LAPACK routine (version 3.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
February 29, 1992
Purpose
=======
DORG2L generates an m by n real matrix Q with orthonormal columns,
which is defined as the last n columns of a product of k elementary
reflectors of order m
Q = H(k) . . . H(2) H(1)
as returned by DGEQLF.
Arguments
=========
M (input) INTEGER
The number of rows of the matrix Q. M >= 0.
N (input) INTEGER
The number of columns of the matrix Q. M >= N >= 0.
K (input) INTEGER
The number of elementary reflectors whose product defines the
matrix Q. N >= K >= 0.
A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
On entry, the (n-k+i)-th column must contain the vector which
defines the elementary reflector H(i), for i = 1,2,...,k, as
returned by DGEQLF in the last k columns of its array
argument A.
On exit, the m by n matrix Q.
LDA (input) INTEGER
The first dimension of the array A. LDA >= max(1,M).
TAU (input) DOUBLE PRECISION array, dimension (K)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by DGEQLF.
WORK (workspace) DOUBLE PRECISION array, dimension (N)
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value
=====================================================================
Test the input arguments
Parameter adjustments */
/* Table of constant values */
static integer c__1 = 1;
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3;
doublereal d__1;
/* Local variables */
static integer i__, j, l;
extern /* Subroutine */ HYPRE_Int dscal_(integer *, doublereal *, doublereal *,
integer *), dlarf_(char *, integer *, integer *, doublereal *,
integer *, doublereal *, doublereal *, integer *, doublereal *);
static integer ii;
extern /* Subroutine */ HYPRE_Int xerbla_(char *, integer *);
#define a_ref(a_1,a_2) a[(a_2)*a_dim1 + a_1]
a_dim1 = *lda;
a_offset = 1 + a_dim1 * 1;
a -= a_offset;
--tau;
--work;
/* Function Body */
*info = 0;
if (*m < 0) {
*info = -1;
} else if (*n < 0 || *n > *m) {
*info = -2;
} else if (*k < 0 || *k > *n) {
*info = -3;
} else if (*lda < max(1,*m)) {
*info = -5;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DORG2L", &i__1);
return 0;
}
/* Quick return if possible */
if (*n <= 0) {
return 0;
}
/* Initialise columns 1:n-k to columns of the unit matrix */
i__1 = *n - *k;
for (j = 1; j <= i__1; ++j) {
i__2 = *m;
for (l = 1; l <= i__2; ++l) {
a_ref(l, j) = 0.;
/* L10: */
}
a_ref(*m - *n + j, j) = 1.;
/* L20: */
}
i__1 = *k;
for (i__ = 1; i__ <= i__1; ++i__) {
ii = *n - *k + i__;
/* Apply H(i) to A(1:m-k+i,1:n-k+i) from the left */
a_ref(*m - *n + ii, ii) = 1.;
i__2 = *m - *n + ii;
i__3 = ii - 1;
dlarf_("Left", &i__2, &i__3, &a_ref(1, ii), &c__1, &tau[i__], &a[
a_offset], lda, &work[1]);
i__2 = *m - *n + ii - 1;
d__1 = -tau[i__];
dscal_(&i__2, &d__1, &a_ref(1, ii), &c__1);
a_ref(*m - *n + ii, ii) = 1. - tau[i__];
/* Set A(m-k+i+1:m,n-k+i) to zero */
i__2 = *m;
for (l = *m - *n + ii + 1; l <= i__2; ++l) {
a_ref(l, ii) = 0.;
/* L30: */
}
/* L40: */
}
return 0;
/* End of DORG2L */
} /* dorg2l_ */
#undef a_ref