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dft_tools/triqs/arrays/expression_template/matrix_algebra.hpp
Olivier Parcollet b534936589 Fix matrix * alias issue and adapt det_manip
- The previous version of the * operator for matrix was too clever.
It was giving a lazy object and then rewriting C = A *B into gemm (a,A,B,0,C).
The pb was in case of aliasing : when e.g. C = A, or is a part of A.
gemm is not correct that case, and as a result generic code like
a = a *b
may not be correct in matrix case, which is unacceptable.

- So we revert to a simple * operator for matrix
that does immediate computation.
Same thing for matrix* vector

- we also suppress a_x_ty class.

-> for M = a * b,
when M is a matrix, there is no overhead due to move assignment
-> however, when M is a view, there is an additionnal copy.

-Correctness comes first, hence the fix.
However, if one wants more speed and one can guarantee that
there is no aliasing possible, then one has to write a direct gemm call.

-> det_manip class was adapted, since in that case, we can show there
no alias, and we want the speed gain, so the * ops where replaced
by direct blas call (using the array blas interface).

-> also gemm, gemv, ger were overloaded in the case the return
matrix/vector (i.e. last parameter of the function) is not an lvalue,
but a temporary view created on the fly.
2013-09-11 18:49:22 +02:00

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C++

/*******************************************************************************
*
* TRIQS: a Toolbox for Research in Interacting Quantum Systems
*
* Copyright (C) 2011 by O. Parcollet
*
* TRIQS is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* TRIQS. If not, see <http://www.gnu.org/licenses/>.
*
******************************************************************************/
#ifndef TRIQS_ARRAYS_EXPRESSION_MATRIX_ALGEBRA_H
#define TRIQS_ARRAYS_EXPRESSION_MATRIX_ALGEBRA_H
#include "./vector_algebra.hpp"
#include "../matrix.hpp"
#include "../linalg/det_and_inverse.hpp"
#include "../blas_lapack/gemv.hpp"
#include "../blas_lapack/gemm.hpp"
namespace triqs { namespace arrays {
// matrix * matrix
template<typename A, typename B, typename Enable = void> struct _matmul_rvalue {};
template<typename A, typename B> struct _matmul_rvalue<A,B, ENABLE_IFC(ImmutableMatrix<A>::value && ImmutableMatrix<B>::value)> {
typedef typename std::remove_const<typename A::value_type>::type V1;
typedef typename std::remove_const<typename B::value_type>::type V2;
typedef matrix<typename std::decay<decltype( V1{} * V2{})>::type> type;
};
template<typename A, typename B>
typename _matmul_rvalue<A,B>::type
operator * (A const & a, B const & b) {
if (second_dim(a) != first_dim(b)) TRIQS_RUNTIME_ERROR<< "Matrix product : dimension mismatch in A*B "<< a<<" "<< b;
auto R = typename _matmul_rvalue<A,B>::type( first_dim(a), second_dim(b));
blas::gemm(1.0,a, b, 0.0, R);
return R;
}
// matrix * vector
template<typename M, typename V, typename Enable = void> struct _mat_vec_mul_rvalue {};
template<typename M, typename V> struct _mat_vec_mul_rvalue<M,V, ENABLE_IFC(ImmutableMatrix<M>::value && ImmutableVector<V>::value)> {
typedef typename std::remove_const<typename M::value_type>::type V1;
typedef typename std::remove_const<typename V::value_type>::type V2;
typedef vector<typename std::decay<decltype(V1{} * V2{})>::type> type;
};
template<typename M, typename V>
typename _mat_vec_mul_rvalue<M,V>::type
operator * (M const & m, V const & v) {
if (second_dim(m) != v.size()) TRIQS_RUNTIME_ERROR<< "Matrix product : dimension mismatch in Matrix*Vector "<< m<<" "<< v;
auto R = typename _mat_vec_mul_rvalue<M,V>::type(first_dim(m));
blas::gemv(1.0,m,v,0.0,R);
return R;
}
// expression template
template<typename Tag, typename L, typename R, bool scalar_are_diagonal_matrices= false>
struct matrix_expr : TRIQS_CONCEPT_TAG_NAME(ImmutableMatrix) {
typedef typename keeper_type<L,scalar_are_diagonal_matrices>::type L_t;
typedef typename keeper_type<R,scalar_are_diagonal_matrices>::type R_t;
static_assert( get_rank<R_t>::value==0 || get_rank<L_t>::value==0 || get_rank<L_t>::value == get_rank<R_t>::value, "rank mismatch in matrix operations");
typedef typename std::result_of<operation<Tag>(typename L_t::value_type,typename R_t::value_type)>::type value_type;
typedef typename std::remove_cv< typename std::remove_reference<typename std::result_of<combine_domain(L_t,R_t)>::type>::type>::type domain_type;
L_t l; R_t r;
template<typename LL, typename RR> matrix_expr(LL && l_, RR && r_) : l(std::forward<LL>(l_)), r(std::forward<RR>(r_)) {}
domain_type domain() const { return combine_domain()(l,r); }
//template<typename KeyType> value_type operator[](KeyType && key) const { return operation<Tag>()(l[std::forward<KeyType>(key)] , r[std::forward<KeyType>(key)]);}
template<typename ... Args> value_type operator()(Args && ... args) const { return operation<Tag>()(l(std::forward<Args>(args)...) , r(std::forward<Args>(args)...));}
friend std::ostream &operator <<(std::ostream &sout, matrix_expr const &expr){return sout << "("<<expr.l << " "<<operation<Tag>::name << " "<<expr.r<<")" ; }
};
template<typename L> // a special case : the unary operator !
struct matrix_unary_m_expr : TRIQS_CONCEPT_TAG_NAME(ImmutableMatrix) {
typedef typename keeper_type<L>::type L_t;
typedef typename L_t::value_type value_type;
typedef typename L_t::domain_type domain_type;
L_t l;
template<typename LL> matrix_unary_m_expr(LL && l_) : l(std::forward<LL>(l_)) {}
domain_type domain() const { return l.domain(); }
//template<typename KeyType> value_type operator[](KeyType&& key) const {return -l[key];}
template<typename ... Args> value_type operator()(Args && ... args) const { return -l(std::forward<Args>(args)...);}
friend std::ostream &operator <<(std::ostream &sout, matrix_unary_m_expr const &expr){return sout << '-'<<expr.l; }
};
// Now we can define all the C++ operators ...
#define DEFINE_OPERATOR(TAG, OP, TRAIT1, TRAIT2) \
template<typename A1, typename A2>\
typename std::enable_if<TRAIT1<A1>::value && TRAIT2 <A2>::value, matrix_expr<tags::TAG, A1,A2>>::type\
operator OP (A1 const & a1, A2 const & a2) { return matrix_expr<tags::TAG, A1,A2>(a1,a2);}
DEFINE_OPERATOR(plus, +, ImmutableMatrix,ImmutableMatrix);
DEFINE_OPERATOR(minus, -, ImmutableMatrix,ImmutableMatrix);
DEFINE_OPERATOR(minus, -, ImmutableMatrix,is_in_ZRC);
DEFINE_OPERATOR(minus, -, is_in_ZRC,ImmutableMatrix);
DEFINE_OPERATOR(multiplies, *, is_in_ZRC,ImmutableMatrix);
DEFINE_OPERATOR(multiplies, *, ImmutableMatrix,is_in_ZRC);
DEFINE_OPERATOR(divides, /, ImmutableMatrix,is_in_ZRC);
#undef DEFINE_OPERATOR
// the addition/substraction of diagonal matrix is special : all scalar are diagonal matrices here...
#define DEFINE_OPERATOR(TAG, OP, TRAIT1, TRAIT2) \
template<typename A1, typename A2>\
typename std::enable_if<TRAIT1<A1>::value && TRAIT2 <A2>::value, matrix_expr<tags::TAG, A1,A2,true>>::type\
operator OP (A1 const & a1, A2 const & a2) { return matrix_expr<tags::TAG, A1,A2,true>(a1,a2);}
DEFINE_OPERATOR(plus, +, ImmutableMatrix,is_in_ZRC);
DEFINE_OPERATOR(plus, +, is_in_ZRC,ImmutableMatrix);
DEFINE_OPERATOR(minus, -, ImmutableMatrix,is_in_ZRC);
DEFINE_OPERATOR(minus, -, is_in_ZRC,ImmutableMatrix);
#undef DEFINE_OPERATOR
// the unary is special
template<typename A1> typename std::enable_if<ImmutableMatrix<A1>::value, matrix_unary_m_expr<A1>>::type
operator - (A1 const & a1) { return {a1};}
template<typename A, typename M> // anything / matrix ---> anything * inverse(matrix)
typename boost::lazy_enable_if< ImmutableMatrix<M>, type_of_mult<A, inverse_lazy <M> > >::type
operator/ (A const & a, M const & m) { return a * inverse(m);}
}}//namespace triqs::arrays
#endif