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/* lapack/single/sorg2r.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 integer c__1 = 1;
/*< SUBROUTINE SORG2R( M, N, K, A, LDA, TAU, WORK, INFO ) >*/
/* Subroutine */ int sorg2r_(integer *m, integer *n, integer *k, real *a,
integer *lda, real *tau, real *work, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2;
real r__1;
/* Local variables */
integer i__, j, l;
extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *),
slarf_(char *, integer *, integer *, real *, integer *, real *,
real *, integer *, real *, ftnlen), xerbla_(char *, integer *,
ftnlen);
/* -- 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 */
/* .. Scalar Arguments .. */
/*< INTEGER INFO, K, LDA, M, N >*/
/* .. */
/* .. Array Arguments .. */
/*< REAL A( LDA, * ), TAU( * ), WORK( * ) >*/
/* .. */
/* Purpose */
/* ======= */
/* SORG2R generates an m by n real matrix Q with orthonormal columns, */
/* which is defined as the first n columns of a product of k elementary */
/* reflectors of order m */
/* Q = H(1) H(2) . . . H(k) */
/* as returned by SGEQRF. */
/* 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) REAL array, dimension (LDA,N) */
/* On entry, the i-th column must contain the vector which */
/* defines the elementary reflector H(i), for i = 1,2,...,k, as */
/* returned by SGEQRF in the first 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) REAL array, dimension (K) */
/* TAU(i) must contain the scalar factor of the elementary */
/* reflector H(i), as returned by SGEQRF. */
/* WORK (workspace) REAL array, dimension (N) */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument has an illegal value */
/* ===================================================================== */
/* .. Parameters .. */
/*< REAL ONE, ZERO >*/
/*< PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 ) >*/
/* .. */
/* .. Local Scalars .. */
/*< INTEGER I, J, L >*/
/* .. */
/* .. External Subroutines .. */
/*< EXTERNAL SLARF, SSCAL, XERBLA >*/
/* .. */
/* .. Intrinsic Functions .. */
/*< INTRINSIC MAX >*/
/* .. */
/* .. Executable Statements .. */
/* Test the input arguments */
/*< INFO = 0 >*/
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--tau;
--work;
/* Function Body */
*info = 0;
/*< IF( M.LT.0 ) THEN >*/
if (*m < 0) {
/*< INFO = -1 >*/
*info = -1;
/*< ELSE IF( N.LT.0 .OR. N.GT.M ) THEN >*/
} else if (*n < 0 || *n > *m) {
/*< INFO = -2 >*/
*info = -2;
/*< ELSE IF( K.LT.0 .OR. K.GT.N ) THEN >*/
} else if (*k < 0 || *k > *n) {
/*< INFO = -3 >*/
*info = -3;
/*< ELSE IF( LDA.LT.MAX( 1, M ) ) THEN >*/
} else if (*lda < max(1,*m)) {
/*< INFO = -5 >*/
*info = -5;
/*< END IF >*/
}
/*< IF( INFO.NE.0 ) THEN >*/
if (*info != 0) {
/*< CALL XERBLA( 'SORG2R', -INFO ) >*/
i__1 = -(*info);
xerbla_("SORG2R", &i__1, (ftnlen)6);
/*< RETURN >*/
return 0;
/*< END IF >*/
}
/* Quick return if possible */
/*< >*/
if (*n <= 0) {
return 0;
}
/* Initialise columns k+1:n to columns of the unit matrix */
/*< DO 20 J = K + 1, N >*/
i__1 = *n;
for (j = *k + 1; j <= i__1; ++j) {
/*< DO 10 L = 1, M >*/
i__2 = *m;
for (l = 1; l <= i__2; ++l) {
/*< A( L, J ) = ZERO >*/
a[l + j * a_dim1] = (float)0.;
/*< 10 CONTINUE >*/
/* L10: */
}
/*< A( J, J ) = ONE >*/
a[j + j * a_dim1] = (float)1.;
/*< 20 CONTINUE >*/
/* L20: */
}
/*< DO 40 I = K, 1, -1 >*/
for (i__ = *k; i__ >= 1; --i__) {
/* Apply H(i) to A(i:m,i:n) from the left */
/*< IF( I.LT.N ) THEN >*/
if (i__ < *n) {
/*< A( I, I ) = ONE >*/
a[i__ + i__ * a_dim1] = (float)1.;
/*< >*/
i__1 = *m - i__ + 1;
i__2 = *n - i__;
slarf_("Left", &i__1, &i__2, &a[i__ + i__ * a_dim1], &c__1, &tau[
i__], &a[i__ + (i__ + 1) * a_dim1], lda, &work[1], (
ftnlen)4);
/*< END IF >*/
}
/*< >*/
if (i__ < *m) {
i__1 = *m - i__;
r__1 = -tau[i__];
sscal_(&i__1, &r__1, &a[i__ + 1 + i__ * a_dim1], &c__1);
}
/*< A( I, I ) = ONE - TAU( I ) >*/
a[i__ + i__ * a_dim1] = (float)1. - tau[i__];
/* Set A(1:i-1,i) to zero */
/*< DO 30 L = 1, I - 1 >*/
i__1 = i__ - 1;
for (l = 1; l <= i__1; ++l) {
/*< A( L, I ) = ZERO >*/
a[l + i__ * a_dim1] = (float)0.;
/*< 30 CONTINUE >*/
/* L30: */
}
/*< 40 CONTINUE >*/
/* L40: */
}
/*< RETURN >*/
return 0;
/* End of SORG2R */
/*< END >*/
} /* sorg2r_ */
#ifdef __cplusplus
}
#endif
|
