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dft_tools/doc/reference/c++/gf/gf_retime.rst
Olivier Parcollet bdac3e159c work on doc for gf, and details.
- little details : code cleaning, clang formatting,  along
with documentation writing for c++ gf.
- separated the mesh in small class for better doc.
- work on documentation : reorganize specialisation, ...
2013-12-30 22:32:16 +01:00

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.. highlight:: c
.. _gf_retime:
Real time
===================================================
This is a specialisation of :ref:`gf_and_view` for imaginary Matsubara frequencies.
Synopsis
------------
.. code::
gf<retime, Target, Opt>
The *Target* template parameter can take the following values :
+-------------------------+-----------------------------------------------------+
| Target | Meaning |
+=========================+=====================================================+
| scalar_valued | The function is scalar valued (double, complex...). |
+-------------------------+-----------------------------------------------------+
| matrix_valued [default] | The function is matrix valued. |
+-------------------------+-----------------------------------------------------+
Domain & mesh
----------------
CORRECT THIS !! PUT OUT THE C++ impl for doxy doc
The domain is :doxy:`matsubara_freq_domain<triqs::gfs::matsubara_domain>`.
The mesh is :doxy:`matsubara_freq_mesh<triqs::gfs::matsubara_freq_mesh>`.
Singularity
-------------
The singularity is a high frequency expansion, :ref:`gf_tail`.
Evaluation method
---------------------
* Linear interpolation on the mesh.
* Return type :
* If Target==scalar_valued : a complex
* If Target==matrix_valued : an object modeling ImmutableMatrix concept.
* When the point is outside of the mesh, the evaluation of the gf returns :
* the evaluation of the high frequency tail if no_tail is not set.
* 0 otherwise
Data storage
---------------
* If Target==scalar_valued :
* `data_t` : 1d array of complex<double>.
* g.data()(i) is the value of g for the i-th point of the mesh.
* If Target==matrix_valued :
* `data_t` : 3d array (C ordered) of complex<double>.
* g.data()(i, range(), range()) is the value of g for the i-th point of the mesh.
HDF5 storage convention
---------------------------
h5 tag : `ReTime`
Examples
---------
.. compileblock::
#include <triqs/gfs.hpp>
using namespace triqs::gfs;
int main() {
double tmin=0, tmax=10; // the time interval
auto n_times=100; // we will have 100 points
//we want a 2x2 matrix-valued Green function
auto g=gf<retime>{ {tmin, tmax, n_times} , {2,2} };
};