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dft_tools/doc/reference/clef/function_0.cpp
tayral edd1ff4529 Restructuring documentation.
A first general restructuration of the doc according to the pattern [tour|tutorial|reference].
In the reference part, objects are documented per topic.
In each topic, [definition|c++|python|hdf5] (not yet implemented)
2014-10-18 12:21:08 +01:00

47 lines
1.3 KiB
C++

#include <triqs/clef.hpp>
#include <iostream>
using namespace triqs::clef;
int main() {
placeholder<0> x_;
placeholder<1> y_;
{ // with one variable
auto f = make_function(2 * x_ + 1, x_);
std::cout << f(3) << std::endl;
std::function<double(double)> F(f);
}
{ // with two variables
auto f = make_function(2 * x_ + y_ + 1, x_, y_);
std::cout << f(3, 4) << std::endl;
std::function<double(double, double)> F(f);
}
{ // Make a function partially
auto f = make_function(2 * x_ + y_ + 1, x_);
// f is a lazy expression expression with placeholder y_, returning a function...
auto f1 = eval(f, y_ = 1); // f1 is a function x-> 2*x + 2
std::cout << f1(10) << std::endl;
}
{ // Currying a function
// auto f = make_function ( make_function( 2*x_ + y_ + 1, x_), y_);
auto f = y_ >> (x_ >> 2 * x_ + y_ + 1);
// f a function y-> x-> 2x+y+1
// f(y) returns a function x-> 2x+y+1
auto g = f(3);
std::cout << g(10) << std::endl;
}
{ // playing with clef::function and std::function
triqs::clef::function<double(double, double)> f2, g2;
f2(x_, y_) = x_ + y_;
std::cout << f2(2, 3) << std::endl;
std::function<double(double, double)> sf2 = f2;
std::cout << sf2(2, 3) << std::endl;
g2(x_, y_) = x_ - y_ + f2(x_, 2 * y_);
std::function<double(double)> sf = x_ >> 2 * x_ + 1;
std::cout << sf(3) << std::endl;
}
}