https://github.com/cometscome/rscg_cpp

The Reduced-Shifted Conjugate-Gradient Method method to calculate the element of the Green's function matrix. See, Y. Nagai, Y. Shinohara, Y. Futamura, and T. Sakurai,[arXiv:1607.03992v2 or DOI:10.7566/JPSJ.86.014708]. http://dx.doi.org/10.7566/JPSJ.86.014708
https://github.com/cometscome/rscg_cpp

Last synced: over 1 year ago
JSON representation

The Reduced-Shifted Conjugate-Gradient Method method to calculate the element of the Green's function matrix. See, Y. Nagai, Y. Shinohara, Y. Futamura, and T. Sakurai,[arXiv:1607.03992v2 or DOI:10.7566/JPSJ.86.014708]. http://dx.doi.org/10.7566/JPSJ.86.014708

• Host: GitHub
• URL: https://github.com/cometscome/rscg_cpp
• Owner: cometscome
• Created: 2019-05-23T09:10:17.000Z (about 7 years ago)
• Default Branch: master
• Last Pushed: 2019-06-02T11:39:00.000Z (about 7 years ago)
• Last Synced: 2025-01-21T10:08:28.199Z (over 1 year ago)
• Language: C++
• Size: 70.3 KB
• Stars: 0
• Watchers: 1
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

README

          
# RSCG_cpp

This is made for c++11.

This package can calculate the elements of the Green's function:

```math

G_ij(σk) = ([σj I - A]^-1)_{ij},

```

with the use of the reduced-shifted conjugate gradient method

(See, Y. Nagai, Y. Shinohara, Y. Futamura, and T. Sakurai,[arXiv:1607.03992v2 or DOI:10.7566/JPSJ.86.014708]).

One can obtain ``G_{ij}(\sigma_k)`` with different frequencies ``\sigma_k``, simultaneously.

The matrix should be symmetric or hermitian.

This is to understand the method. 

I do not guarantee result with the use of this code. 

```c++

#include 

#include 

#include 

#include 

#include "rscg.cpp"

using namespace std;

template 

vector  matmul(const std::array,N> &H, vector  &x){

    vector  Ax(N);

    for(int i = 0; i < N; i++){

        for(int j = 0; j < N; j++){

        Ax[i] += H[i][j]*x[j];

        };

    };

    return Ax;

};

int main() {

    std::array, 3> H{ {

        { 1, 0, 3 },

        { 0, 2, 0 },

        { 3, 0, 5 }

    } };

    vector  x(3,1.0);

    auto f = std::bind(matmul<3>,H,std::placeholders::_1);

    RSCG* rscg;

    rscg = new RSCG(3,f);

    vector > vec_z(2,0.2);

    vec_z[0] = 0.2*1i;

    vec_z[1] = 4.0 + 0.5*1i;

    cout << vec_z[0] << std::endl;

    vector > Gij = rscg->calc_greenfunction_realH(0,0,vec_z);

    cout << "RSCG" << Gij[0] << " exact: 1.12377 - 0.383299 I" << std::endl;

    cout << "RSCG" << Gij[1] << " exact: 0.0844022 - 0.0339264 I" <