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- //
- // Copyright (c) 2018-2019, Cem Bassoy, cem.bassoy@gmail.com
- //
- // Distributed under the Boost Software License, Version 1.0. (See
- // accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- //
- // The authors gratefully acknowledge the support of
- // Fraunhofer IOSB, Ettlingen, Germany
- //
- #include <boost/numeric/ublas/tensor.hpp>
- #include <boost/multiprecision/cpp_bin_float.hpp>
- #include <ostream>
- int main()
- {
- using namespace boost::numeric::ublas;
- using namespace boost::multiprecision;
- // creates a three-dimensional tensor with extents 3,4 and 2
- // tensor A stores single-precision floating-point number according
- // to the first-order storage format
- using ftype = float;
- auto A = tensor<ftype>{3,4,2};
- // initializes the tensor with increasing values along the first-index
- // using a single index.
- auto vf = ftype(0);
- for(auto i = 0u; i < A.size(); ++i, vf += ftype(1))
- A[i] = vf;
- // formatted output
- std::cout << "% --------------------------- " << std::endl;
- std::cout << "% --------------------------- " << std::endl << std::endl;
- std::cout << "A=" << A << ";" << std::endl << std::endl;
- // creates a four-dimensional tensor with extents 5,4,3 and 2
- // tensor A stores complex floating-point extended double precision numbers
- // according to the last-order storage format
- // and initializes it with the default value.
- using ctype = std::complex<cpp_bin_float_double_extended>;
- auto B = tensor<ctype,last_order>(shape{5,4,3,2},ctype{});
- // initializes the tensor with increasing values along the last-index
- // using a single-index
- auto vc = ctype(0,0);
- for(auto i = 0u; i < B.size(); ++i, vc += ctype(1,1))
- B[i] = vc;
- // formatted output
- std::cout << "% --------------------------- " << std::endl;
- std::cout << "% --------------------------- " << std::endl << std::endl;
- std::cout << "B=" << B << ";" << std::endl << std::endl;
- auto C = tensor<ctype,last_order>(B.extents());
- // computes the complex conjugate of elements of B
- // using multi-index notation.
- for(auto i = 0u; i < B.size(0); ++i)
- for(auto j = 0u; j < B.size(1); ++j)
- for(auto k = 0u; k < B.size(2); ++k)
- for(auto l = 0u; l < B.size(3); ++l)
- C.at(i,j,k,l) = std::conj(B.at(i,j,k,l));
- std::cout << "% --------------------------- " << std::endl;
- std::cout << "% --------------------------- " << std::endl << std::endl;
- std::cout << "C=" << C << ";" << std::endl << std::endl;
- // computes the complex conjugate of elements of B
- // using iterators.
- auto D = tensor<ctype,last_order>(B.extents());
- std::transform(B.begin(), B.end(), D.begin(), [](auto const& b){ return std::conj(b); });
- std::cout << "% --------------------------- " << std::endl;
- std::cout << "% --------------------------- " << std::endl << std::endl;
- std::cout << "D=" << D << ";" << std::endl << std::endl;
- // reshaping tensors.
- auto new_extents = B.extents().base();
- std::next_permutation( new_extents.begin(), new_extents.end() );
- D.reshape( shape(new_extents) );
- std::cout << "% --------------------------- " << std::endl;
- std::cout << "% --------------------------- " << std::endl << std::endl;
- std::cout << "newD=" << D << ";" << std::endl << std::endl;
- }
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