libeisdrt manual

libeisdrt is a c++ shared library to compute Distribution of Relaxation Times using Tikhonov regularization. libeisdrt is well integrated to eisgenerator, Eigen and PyTorch.

This manual is divided in the following sections depending on what datatypes you want to use libeisdrt with:

• Eigen API api to use in Eigen applications
• libtorch API api to use in libtorch/PyTorch applications
• eisgenerator API api to use in eisgenerator applications
• types types used by all apis

Building

the main development platform of libeisdrt is Linux, and libeisdrt works best on UNIX-like systems, however libeisdrt is fully portable and should compile on any platform that supports the requirements below

Requirements

• git is required to get the source
• a C++20 compliant compiler like GCC
• cmake version 3.19 or later
• libtorch is optional, but is required for libtorch Tensor support
• eisgenerator is optional, but is required for eisgenerator DataPoint support
• PkgConfig is optional, but is required for eisgenerator support
• eigen version 4.0 or later

Procedure

$ git clone https://git-ce.rwth-aachen.de/carl_philipp.klemm/libdrt
$ mkdir libdrt/build
$ cd libdrt/build
$ cmake ..
$ make
$ make install
$ make doc

Usage

The usage of this library can be inferred from the API documentation linked above and from the following eisgenerator based example.

Example usage:

#include <iostream>
#include <eisgenerator/model.h>
#include <eisgenerator/eistype.h>
#include <eisdrt/eisdrt.h>
 
void printImpedance(const std::vector<eis::DataPoint>& data)
{
        std::cout<<'[';
        size_t colcount = 0;
        for(const eis::DataPoint& point : data)
        {
                std::cout<<point.im;
                std::cout<<' ';
                if(++colcount > 1)
                {
                        std::cout<<'\n';
                        colcount = 0;
                }
        }
        std::cout<<"]\n";
}
 
void printFvalueVector(const std::vector<fvalue>& data)
{
        std::cout<<'[';
        size_t colcount = 0;
        for(fvalue point : data)
        {
                std::cout<<point;
                std::cout<<' ';
                if(++colcount > 1)
                {
                        std::cout<<'\n';
                        colcount = 0;
                }
        }
        std::cout<<"]\n";
}
 
int main(int argc, char** argv)
{
        std::cout<<std::scientific;
 
        // specify the angular frequency range of the spectra to be
        // simulated to be 1-1*10^6 Hz with 3 steps and log10 distrobution
        eis::Range omega(1, 1e6, 3, true);
 
        // specify circuit to be simulated
        eis::Model model("r{10}-r{50}p{0.02, 0.8}");
 
        // execute a simulation
        std::vector<eis::DataPoint> data = model.executeSweep(omega);
 
        // print the specrum
        printImpedance(data);
 
        // allocate a FitMetrics struct on the stack
        FitMetrics fm;
 
        // calculate the drt for this spectrum
        std::vector<fvalue> x = calcDrt(data, fm, FitParameters(1000));
 
        // print some info on the drt
        std::cout<<"Iterations: "<<fm.iterations<<'\n';
        std::cout<<"fx "<<fm.fx<<"\ndrt: ";
        printFvalueVector(x);
 
        return 0;
}

License

libeisdrt is licensed to you under the LGPL version 3 , or (at your option) any later version. see lgpl-3.0.txt or LGPL for details