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https://github.com/triqs/dft_tools
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71 lines
2.2 KiB
ReStructuredText
71 lines
2.2 KiB
ReStructuredText
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.. highlight:: c
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.. _arr_simple_fun:
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Simple array functions
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==================================
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The following functions work for any object modeling :ref:`ImmutableCuboidArray` concept.
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In this section, we present some simple functions already in the library.
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It is however very easy to create new one using the usual functional constructions :ref:`map and fold<arr_map_fold>`.
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Element-wise functions
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---------------------------
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The following functions are mapped on the array (using :ref:`map`):
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`abs real imag pow cos sin tan cosh sinh tanh acos asin atan exp log sqrt floor`
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meaning that e.g. if `A` is an array,
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real(A) models :ref:`ImmutableCuboidArray`, with the same size and returns the real part of the elements.
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In other words, it applies the function term-by-term.
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.. note::
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These functions do NOT compute a new array in memory, they are lazy.
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sum
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---------------
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**Synopsis**::
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template<ImmutableCuboidArray A> A::value_type sum (A const &);
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template<ImmutableCuboidArray A> A::value_type prod (A const &);
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Returns the sum (resp. product) of the all the elements of the array.
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max_element, min_element
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-------------------------------
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**Synopsis**::
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template<ImmutableCuboidArray A> A::value_type max_element (A const &);
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template<ImmutableCuboidArray A> A::value_type min_element (A const &);
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Returns the maximum/minimum element of the array (provided that value_type is an ordered type of course...).
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Examples
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-----------------
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.. compileblock::
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#include <triqs/arrays.hpp>
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#include <triqs/arrays/algorithms.hpp>
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using triqs::arrays::matrix; using triqs::clef::placeholder;
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int main() {
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// declare and init a matrix
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placeholder<0> i_; placeholder<1> j_;
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matrix<int> A (2,2); A(i_,j_) << i_ - j_ ;
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std::cout << "A = " << A << std::endl;
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std::cout << "abs(A)= " << matrix<double>(abs(A)) << std::endl;
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std::cout << "sum(A) = " << sum(A) << std::endl;
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std::cout << "max_element(A) = " << max_element(A) << std::endl;
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std::cout << "min_element(A) = " << min_element(A) << std::endl;
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std::cout << "min_element(abs(A)) = " << min_element(abs(A)) << std::endl;
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}
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