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https://github.com/triqs/dft_tools
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b534936589
- 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.
56 lines
1.9 KiB
C++
56 lines
1.9 KiB
C++
/*******************************************************************************
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*
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* TRIQS: a Toolbox for Research in Interacting Quantum Systems
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*
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* Copyright (C) 2011 by O. Parcollet
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*
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* TRIQS is free software: you can redistribute it and/or modify it under the
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* terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* TRIQS. If not, see <http://www.gnu.org/licenses/>.
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*
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******************************************************************************/
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#include "./common.hpp"
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#include "./src/linalg/eigenelements.hpp"
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#include "./src/blas_lapack/stev.hpp"
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using namespace triqs::arrays;
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using namespace triqs;
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int main(int argc, char **argv) {
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arrays::vector<double> D (5), DD(4);
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for (size_t i=0; i<5; ++i) {D(i) = 3.2*i+2.3;}
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for (size_t i=0; i<4; ++i) {DD(i) = 2.4*(i+1.82) + 0.78;}
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auto R = range(0,5);
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blas::tridiag_worker w(10);
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w(D,DD);
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std::cerr<<" values = "<< w.values()<<std::endl;
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std::cerr<<" vectors = "<< w.vectors()(R,R)<<std::endl;
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//check
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matrix<double> A(5,5); A()=0;
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for (size_t i=0; i<5; ++i) A(i,i) = D(i);
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for (size_t i=0; i<4; ++i) { A(i,i+1) = DD(i); A(i+1,i) = DD(i);}
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std::cerr<<"A = "<<A<<std::endl;
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linalg::eigenelements_worker< matrix_view <double>, true> w2 (A());
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w2.invoke();
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std::cerr<<" check values = "<< w2.values()<<std::endl;
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std::cerr<<" check vectors = "<< w2.vectors()<<std::endl;
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assert_all_close(w.vectors()(R,R), w2.vectors(), 1.e-10);
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assert_all_close(array_view<double,1>(w.values()), w2.values(), 1.e-10);
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return 0;
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}
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