// Copyright (C) 2010 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_LAPACk_ORMQR_Hh_
#define DLIB_LAPACk_ORMQR_Hh_
#include "fortran_id.h"
#include "../matrix.h"
namespace dlib
{
namespace lapack
{
namespace binding
{
extern "C"
{
void DLIB_FORTRAN_ID(dormqr) (const char *side, const char *trans, const integer *m, const integer *n,
const integer *k, const double *a, const integer *lda, const double *tau,
double * c_, const integer *ldc, double *work, const integer *lwork,
integer *info);
void DLIB_FORTRAN_ID(sormqr) (const char *side, const char *trans, const integer *m, const integer *n,
const integer *k, const float *a, const integer *lda, const float *tau,
float * c_, const integer *ldc, float *work, const integer *lwork,
integer *info);
}
inline int ormqr (char side, char trans, integer m, integer n,
integer k, const double *a, integer lda, const double *tau,
double *c_, integer ldc, double *work, integer lwork)
{
integer info = 0;
DLIB_FORTRAN_ID(dormqr)(&side, &trans, &m, &n,
&k, a, &lda, tau,
c_, &ldc, work, &lwork, &info);
return info;
}
inline int ormqr (char side, char trans, integer m, integer n,
integer k, const float *a, integer lda, const float *tau,
float *c_, integer ldc, float *work, integer lwork)
{
integer info = 0;
DLIB_FORTRAN_ID(sormqr)(&side, &trans, &m, &n,
&k, a, &lda, tau,
c_, &ldc, work, &lwork, &info);
return info;
}
}
// ------------------------------------------------------------------------------------
/* -- LAPACK routine (version 3.1) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DORMQR overwrites the general real M-by-N matrix C with */
/* SIDE = 'L' SIDE = 'R' */
/* TRANS = 'N': Q * C C * Q */
/* TRANS = 'T': Q**T * C C * Q**T */
/* where Q is a real orthogonal matrix defined as the product of k */
/* elementary reflectors */
/* Q = H(1) H(2) . . . H(k) */
/* as returned by DGEQRF. Q is of order M if SIDE = 'L' and of order N */
/* if SIDE = 'R'. */
/* Arguments */
/* ========= */
/* SIDE (input) CHARACTER*1 */
/* = 'L': apply Q or Q**T from the Left; */
/* = 'R': apply Q or Q**T from the Right. */
/* TRANS (input) CHARACTER*1 */
/* = 'N': No transpose, apply Q; */
/* = 'T': Transpose, apply Q**T. */
/* M (input) INTEGER */
/* The number of rows of the matrix C. M >= 0. */
/* N (input) INTEGER */
/* The number of columns of the matrix C. N >= 0. */
/* K (input) INTEGER */
/* The number of elementary reflectors whose product defines */
/* the matrix Q. */
/* If SIDE = 'L', M >= K >= 0; */
/* if SIDE = 'R', N >= K >= 0. */
/* A (input) DOUBLE PRECISION array, dimension (LDA,K) */
/* The i-th column must contain the vector which defines the */
/* elementary reflector H(i), for i = 1,2,...,k, as returned by */
/* DGEQRF in the first k columns of its array argument A. */
/* A is modified by the routine but restored on exit. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. */
/* If SIDE = 'L', LDA >= max(1,M); */
/* if SIDE = 'R', LDA >= max(1,N). */
/* TAU (input) DOUBLE PRECISION array, dimension (K) */
/* TAU(i) must contain the scalar factor of the elementary */
/* reflector H(i), as returned by DGEQRF. */
/* C (input/output) DOUBLE PRECISION array, dimension (LDC,N) */
/* On entry, the M-by-N matrix C. */
/* On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q. */
/* LDC (input) INTEGER */
/* The leading dimension of the array C. LDC >= max(1,M). */
/* WORK (workspace/output) DOUBLE PRECISION array, dimension (MAX(1,LWORK)) */
/* On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */
/* LWORK (input) INTEGER */
/* The dimension of the array WORK. */
/* If SIDE = 'L', LWORK >= max(1,N); */
/* if SIDE = 'R', LWORK >= max(1,M). */
/* For optimum performance LWORK >= N*NB if SIDE = 'L', and */
/* LWORK >= M*NB if SIDE = 'R', where NB is the optimal */
/* blocksize. */
/* If LWORK = -1, then a workspace query is assumed; the routine */
/* only calculates the optimal size of the WORK array, returns */
/* this value as the first entry of the WORK array, and no error */
/* message related to LWORK is issued by XERBLA. */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
// ------------------------------------------------------------------------------------
template <
typename T,
long NR1, long NR2, long NR3,
long NC1, long NC2, long NC3,
typename MM,
typename C_LAYOUT
>
int ormqr (
char side,
char trans,
const matrix<T,NR1,NC1,MM,column_major_layout>& a,
const matrix<T,NR2,NC2,MM,column_major_layout>& tau,
matrix<T,NR3,NC3,MM,C_LAYOUT>& c
)
{
long m = c.nr();
long n = c.nc();
const long k = a.nc();
long ldc;
if (is_same_type<C_LAYOUT,column_major_layout>::value)
{
ldc = c.nr();
}
else
{
// Since lapack expects c to be in column major layout we have to
// do something to make this work. Since a row major layout matrix
// will look just like a transposed C we can just swap a few things around.
ldc = c.nc();
swap(m,n);
if (side == 'L')
side = 'R';
else
side = 'L';
if (trans == 'T')
trans = 'N';
else
trans = 'T';
}
matrix<T,0,1,MM,column_major_layout> work;
// figure out how big the workspace needs to be.
T work_size = 1;
int info = binding::ormqr(side, trans, m, n,
k, &a(0,0), a.nr(), &tau(0,0),
&c(0,0), ldc, &work_size, -1);
if (info != 0)
return info;
if (work.size() < work_size)
work.set_size(static_cast<long>(work_size), 1);
// compute the actual result
info = binding::ormqr(side, trans, m, n,
k, &a(0,0), a.nr(), &tau(0,0),
&c(0,0), ldc, &work(0,0), work.size());
return info;
}
// ------------------------------------------------------------------------------------
}
}
// ----------------------------------------------------------------------------------------
#endif // DLIB_LAPACk_ORMQR_Hh_