mirror of
https://github.com/triqs/dft_tools
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24 lines
1.1 KiB
C++
24 lines
1.1 KiB
C++
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#include <triqs/det_manip/det_manip.hpp>
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struct fun {
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typedef double result_type;
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typedef double argument_type;
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double operator()(double x, double y) const { return (exp(x) - y * y); }
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};
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int main() {
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triqs::det_manip::det_manip<fun> D(fun(), std::vector<double>{1, 2, 2.5}, std::vector<double>{3, 4, 9});
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std::cout << std::endl << "After construction, D.matrix()=" << D.matrix() << std::endl << std::endl;
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int i0 = 2, i1 = 1, j0 = 0, j1 = 1; // number of the removed lines and columns
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std::cout << "We want to remove 2 lines and 2 columns for i0=" << i0 << ", j0=" << j0 << ", i1=" << i1 << ", j1=" << j1 << "."
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<< std::endl;
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// (try of) removal of a line and a column at position (1,0) in the matrix.
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double detratio = D.try_remove2(i0, i1, j0, j1); // the ratio between new and old determinants
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// while the operation is not complete, the matrix stays unchanged
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std::cout << "After try_remove2, D.matrix()=" << D.matrix() << std::endl;
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// here we validate the removal: the (inverse) matrix and determinant are updated
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D.complete_operation();
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std::cout << "After complete_operation, D.matrix()=" << D.matrix() << std::endl << std::endl;
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}
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