mirror of
https://github.com/triqs/dft_tools
synced 2024-12-25 13:53:40 +01:00
3fe400d34c
- examples split from the rst file using a python script (split_code). - Final result for the doc is unchanged. - examples are compiled and tested with the other tests. - examples' code have been clang-formatted, with triqs style. - doc compiles much faster, and with the same options as the rest of the test. - examples are added as tests, so they are run by make test, as simple C tests. - done for the tutorials and the reference. - autocompile removed (changed into triqs_example directive). - add triqs_example : - make a literal include of the source code. - runs the compiled example - add, as before, the result to the source code in the doc. - added the script split_code, used to make the changes automatically, maybe for later reuse. (in _tools)
64 lines
2.4 KiB
C++
64 lines
2.4 KiB
C++
#include <triqs/clef.hpp>
|
|
#include <triqs/arrays.hpp>
|
|
#include <iostream>
|
|
#include <algorithm>
|
|
int main() {
|
|
// Declaring some placeholders (i.e. dummy variables).
|
|
triqs::clef::placeholder<0> i_;
|
|
triqs::clef::placeholder<1> j_;
|
|
|
|
// Declaring a 3x3 matrix
|
|
triqs::arrays::matrix<double> A(3, 3);
|
|
|
|
// Automatically filling the matrix
|
|
// -> forget about the bounds, it is automatic
|
|
// -> forget about the best order to order the for loops for performance, it is also automatic
|
|
A(i_, j_) << i_ + 2 * j_;
|
|
|
|
// Cheking the result
|
|
std::cout << A << std::endl;
|
|
|
|
// It also works for std container: we just have to add a call clef::make_expr function
|
|
std::vector<double> V(10);
|
|
double pi = std::acos(-1);
|
|
|
|
// Automatically filling the vector with the evaluation of the expression in i_
|
|
triqs::clef::make_expr(V)[i_] << cos(2 * pi / 5.0 * i_);
|
|
|
|
// -> by the way, the constant calculation is precomputed
|
|
// (expressions are partially evaluated as soon as possible)
|
|
// illustration :
|
|
// the time_consuming_function will be called only once in the loop, while cos is called 10 times
|
|
auto time_consuming_function = [](double x) {
|
|
std::cout << "call time_consuming_function" << std::endl;
|
|
return 2 * x;
|
|
};
|
|
triqs::clef::make_expr(V)[i_] << cos(time_consuming_function(10) * i_);
|
|
|
|
// If you insist using on more complex containers...
|
|
std::vector<std::vector<double>> W(3, std::vector<double>(5));
|
|
triqs::clef::make_expr(W)[i_][j_] << i_ + cos(time_consuming_function(10) * j_ + i_);
|
|
|
|
// You can also put a CLEF expression in a std::function
|
|
// a function i -> 2*i +1
|
|
std::function<int(int)> f = i_ >> 2 * i_ + 1;
|
|
// a function (i,j) -> 2*i +j
|
|
std::function<double(int, int)> g = var(i_, j_) >> 2 * i_ + j_;
|
|
// checking ...
|
|
std::cout << "f(10) =" << f(10) << " g(1,2) =" << g(1, 2) << std::endl;
|
|
|
|
// You can also use a Curry form : h is a function i-> j -> 2*i+ j
|
|
auto h = i_ >> (j_ >> 2 * i_ + j_);
|
|
std::cout << "h(1)(2) = " << h(1)(2) << std::endl;
|
|
|
|
// You an also use this to quickly write some lambda, as an alternative syntax to the C++ lambda
|
|
// with e.g. STL algorithms (with the advantage that the function is polymorphic!).
|
|
std::vector<int> v = {0, -1, 2, -3, 4, 5, -6};
|
|
// replace all negative elements (i.e. those for which i -> (i<0) return true), by 0
|
|
std::replace_if(begin(v), end(v), i_ >> (i_ < 0), 0);
|
|
// for non believer, it really worked ...
|
|
for (auto const& x : v) std::cout << x << " ";
|
|
std::cout << std::endl;
|
|
}
|
|
|