mirror of
https://github.com/triqs/dft_tools
synced 2024-11-01 03:33:50 +01:00
50 lines
1.3 KiB
ReStructuredText
50 lines
1.3 KiB
ReStructuredText
|
.. highlight:: c
|
||
|
|
|
||
|
|
.. _Lazy:
|
||
|
|
|
||
|
|
Interaction with clef expressions
|
||
|
|
============================================
|
||
|
|
|
||
|
|
* The Value and View classes (array, matrix and vector and algebraic expression of them)
|
||
|
|
are ready to use with the triqs::clef library :
|
||
|
|
|
||
|
|
* They can be called on lazy expressions made of placeholders.
|
||
|
|
|
||
|
|
* Automatic assignment has been set up. Cf clef lib doc ...
|
||
|
|
|
||
|
|
* Using the clef library offers a quick and efficient way to fill an array with multiple advantages :
|
||
|
|
|
||
|
|
* It is simpler and more readeable than a series of for loops.
|
||
|
|
* It is usually more optimal since the for loops are automatically written in the TraversalOrder of the
|
||
|
|
array.
|
||
|
|
|
||
|
|
* NB : the expression can be (and are) inlined by the compilers...
|
||
|
|
|
||
|
|
* **Example** :
|
||
|
|
|
||
|
|
.. compileblock::
|
||
|
|
|
||
|
|
#include <triqs/arrays.hpp>
|
||
|
|
using triqs::arrays::array; using triqs::clef::placeholder;
|
||
|
|
|
||
|
|
int main(){
|
||
|
|
placeholder<0> i_; placeholder<1> j_;
|
||
|
|
array<double,2> A(2,2), B(2,2);
|
||
|
|
|
||
|
|
A(i_,j_) << i_ + 2*j_ ;
|
||
|
|
|
||
|
|
B(i_,j_) << A(j_,i_)/2;
|
||
|
|
|
||
|
|
std::cout << "A = "<<A << std::endl;
|
||
|
|
std::cout << "B = "<<B << std::endl;
|
||
|
|
}
|
||
|
|
|
||
|
|
.. note::
|
||
|
|
The syntax uses a <<, not = since the array is not assigned to an expression
|
||
|
|
but filled by the evaluation thereof.
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|