3
0
mirror of https://github.com/triqs/dft_tools synced 2024-12-27 06:43:40 +01:00
dft_tools/doc/reference/c++/arrays/map_1.cpp
Olivier Parcollet 3fe400d34c doc : split c++ code from rst
- 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)
2014-05-31 23:00:16 +02:00

24 lines
545 B
C++

#include <triqs/arrays.hpp>
#include <triqs/arrays/functional/fold.hpp>
using namespace triqs;
double frobenius_norm(arrays::matrix<double> const& a) {
auto l = [](double r, double x) {
auto ab = std::abs(x);
return r + ab * ab;
};
return std::sqrt(arrays::fold(l)(a, 0));
}
int main() {
// declare and init a matrix
clef::placeholder<0> i_;
clef::placeholder<1> j_;
arrays::matrix<double> A(2, 2);
A(i_, j_) << i_ + j_ / 2.0;
std::cout << "A = " << A << std::endl;
std::cout << "||A|| = " << frobenius_norm(A) << std::endl;
}