mirror of
https://github.com/opencv/opencv.git
synced 2024-12-11 22:59:16 +08:00
158 lines
4.2 KiB
C
158 lines
4.2 KiB
C
/* sgelq2.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 "clapack.h"
|
|
|
|
|
|
/* Subroutine */ int sgelq2_(integer *m, integer *n, real *a, integer *lda,
|
|
real *tau, real *work, integer *info)
|
|
{
|
|
/* System generated locals */
|
|
integer a_dim1, a_offset, i__1, i__2, i__3;
|
|
|
|
/* Local variables */
|
|
integer i__, k;
|
|
real aii;
|
|
extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *,
|
|
integer *, real *, real *, integer *, real *), xerbla_(
|
|
char *, integer *), slarfp_(integer *, real *, real *,
|
|
integer *, real *);
|
|
|
|
|
|
/* -- LAPACK routine (version 3.2) -- */
|
|
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
|
|
/* November 2006 */
|
|
|
|
/* .. Scalar Arguments .. */
|
|
/* .. */
|
|
/* .. Array Arguments .. */
|
|
/* .. */
|
|
|
|
/* Purpose */
|
|
/* ======= */
|
|
|
|
/* SGELQ2 computes an LQ factorization of a real m by n matrix A: */
|
|
/* A = L * Q. */
|
|
|
|
/* Arguments */
|
|
/* ========= */
|
|
|
|
/* 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. */
|
|
|
|
/* A (input/output) REAL array, dimension (LDA,N) */
|
|
/* On entry, the m by n matrix A. */
|
|
/* On exit, the elements on and below the diagonal of the array */
|
|
/* contain the m by min(m,n) lower trapezoidal matrix L (L is */
|
|
/* lower triangular if m <= n); the elements above the diagonal, */
|
|
/* with the array TAU, represent the orthogonal matrix Q as a */
|
|
/* product of elementary reflectors (see Further Details). */
|
|
|
|
/* LDA (input) INTEGER */
|
|
/* The leading dimension of the array A. LDA >= max(1,M). */
|
|
|
|
/* TAU (output) REAL array, dimension (min(M,N)) */
|
|
/* The scalar factors of the elementary reflectors (see Further */
|
|
/* Details). */
|
|
|
|
/* WORK (workspace) REAL array, dimension (M) */
|
|
|
|
/* INFO (output) INTEGER */
|
|
/* = 0: successful exit */
|
|
/* < 0: if INFO = -i, the i-th argument had an illegal value */
|
|
|
|
/* Further Details */
|
|
/* =============== */
|
|
|
|
/* The matrix Q is represented as a product of elementary reflectors */
|
|
|
|
/* Q = H(k) . . . H(2) H(1), where k = min(m,n). */
|
|
|
|
/* Each H(i) has the form */
|
|
|
|
/* H(i) = I - tau * v * v' */
|
|
|
|
/* where tau is a real scalar, and v is a real vector with */
|
|
/* v(1:i-1) = 0 and v(i) = 1; v(i+1:n) is stored on exit in A(i,i+1:n), */
|
|
/* and tau in TAU(i). */
|
|
|
|
/* ===================================================================== */
|
|
|
|
/* .. Parameters .. */
|
|
/* .. */
|
|
/* .. Local Scalars .. */
|
|
/* .. */
|
|
/* .. External Subroutines .. */
|
|
/* .. */
|
|
/* .. Intrinsic Functions .. */
|
|
/* .. */
|
|
/* .. Executable Statements .. */
|
|
|
|
/* Test the input arguments */
|
|
|
|
/* Parameter adjustments */
|
|
a_dim1 = *lda;
|
|
a_offset = 1 + a_dim1;
|
|
a -= a_offset;
|
|
--tau;
|
|
--work;
|
|
|
|
/* Function Body */
|
|
*info = 0;
|
|
if (*m < 0) {
|
|
*info = -1;
|
|
} else if (*n < 0) {
|
|
*info = -2;
|
|
} else if (*lda < max(1,*m)) {
|
|
*info = -4;
|
|
}
|
|
if (*info != 0) {
|
|
i__1 = -(*info);
|
|
xerbla_("SGELQ2", &i__1);
|
|
return 0;
|
|
}
|
|
|
|
k = min(*m,*n);
|
|
|
|
i__1 = k;
|
|
for (i__ = 1; i__ <= i__1; ++i__) {
|
|
|
|
/* Generate elementary reflector H(i) to annihilate A(i,i+1:n) */
|
|
|
|
i__2 = *n - i__ + 1;
|
|
/* Computing MIN */
|
|
i__3 = i__ + 1;
|
|
slarfp_(&i__2, &a[i__ + i__ * a_dim1], &a[i__ + min(i__3, *n)* a_dim1]
|
|
, lda, &tau[i__]);
|
|
if (i__ < *m) {
|
|
|
|
/* Apply H(i) to A(i+1:m,i:n) from the right */
|
|
|
|
aii = a[i__ + i__ * a_dim1];
|
|
a[i__ + i__ * a_dim1] = 1.f;
|
|
i__2 = *m - i__;
|
|
i__3 = *n - i__ + 1;
|
|
slarf_("Right", &i__2, &i__3, &a[i__ + i__ * a_dim1], lda, &tau[
|
|
i__], &a[i__ + 1 + i__ * a_dim1], lda, &work[1]);
|
|
a[i__ + i__ * a_dim1] = aii;
|
|
}
|
|
/* L10: */
|
|
}
|
|
return 0;
|
|
|
|
/* End of SGELQ2 */
|
|
|
|
} /* sgelq2_ */
|