triqs::gfs::fit_tail¶
#include <triqs/gfs.hpp>
Synopsis
template<int N, typename G, typename A = typenameG::data_t::>std::pair<typename A::regular_type, double> fit_tail (G const & g, A const & known_moments = {}) template<int N, typename BG, typename BA = std::vector<typenameBG::g_t::data_t::regular_type>std::pair<std::vector<typename BG::g_t::data_t::regular_type>, double> fit_tail (BG const & bg,BA const & known_moments = {})
Documentation
1) Fit the tail of a Green function using a least-squares fitting procedure
2) Fit the tail of a Block Green function using a least-squares fitting procedure
Template parameters¶
- N The position of the frequency mesh in case of a product mesh [default: 0]
- G The type of the Green function (gf, gf_view, gf_const_view)
- A The type of the high-frequency moment array (array, array_view, array_const_view)
- BG The type of the Block Green function (block_gf, block_gf_view, block_gf_const_view)
- AG The type of the high-frequecy moments for Block Green functions (e.g. std::vector<array>)
Parameters¶
- g The Green function object to fit the tail for
- known_moments The object containing the known high-frequency moments
- bg The Block Green function object to fit the tail for
Returns¶
A pair of the tail object and the fitting error
Example¶
#include <triqs/gfs.hpp>
#include <iomanip>
using namespace triqs::gfs;
triqs::clef::placeholder<0> iw_;
int main() {
double beta = 1.0;
int n_iw = 100;
auto g = gf<imfreq>{{beta, Fermion, n_iw}, {1, 1}};
g[iw_] << 1.0 / iw_;
auto [tail, err] = fit_tail(g);
std::cout << std::setprecision(2) << "Error: " << err << "\nTail: " << tail;
}
Output
Error: 5.4e-19
Tail: [(2.7e-16,-4.2e-17) (1,-1.4e-14) (2.6e-10,-6e-11) (2.1e-09,-8.8e-09) (8.1e-05,-3.2e-05) (-0.00058,-0.0014) (8.4,-2.3) ]