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#include <Eigen/Core>
#include <iostream>
#include "timer.h"
#include <Spectra/SymEigsSolver.h>
#include <Spectra/GenEigsSolver.h>
using namespace Spectra;
using Eigen::MatrixXd;
using Eigen::VectorXd;
using Eigen::MatrixXcd;
using Eigen::VectorXcd;
void eigs_sym_Cpp(MatrixXd &M, VectorXd &init_resid, int k, int m,
double &time_used, double &prec_err, int &nops)
{
double start, end;
start = get_wall_time();
DenseSymMatProd<double> op(M);
SymEigsSolver<DenseSymMatProd<double>> eigs(op, k, m);
eigs.init(init_resid.data());
int nconv = eigs.compute(SortRule::LargestMagn);
int niter = eigs.num_iterations();
nops = eigs.num_operations();
VectorXd evals = eigs.eigenvalues();
MatrixXd evecs = eigs.eigenvectors();
/* std::cout << "computed eigenvalues D = \n" << evals.transpose() << std::endl;
std::cout << "first 5 rows of computed eigenvectors U = \n" << evecs.topRows<5>() << std::endl;
std::cout << "nconv = " << nconv << std::endl;
std::cout << "niter = " << niter << std::endl;
std::cout << "nops = " << nops << std::endl; */
end = get_wall_time();
time_used = (end - start) * 1000;
MatrixXd err = M * evecs - evecs * evals.asDiagonal();
prec_err = err.cwiseAbs().maxCoeff();
}
void eigs_gen_Cpp(MatrixXd &M, VectorXd &init_resid, int k, int m,
double &time_used, double &prec_err, int &nops)
{
double start, end;
start = get_wall_time();
DenseGenMatProd<double> op(M);
GenEigsSolver<DenseGenMatProd<double>> eigs(op, k, m);
eigs.init(init_resid.data());
int nconv = eigs.compute(SortRule::LargestMagn);
int niter = eigs.num_iterations();
nops = eigs.num_operations();
VectorXcd evals = eigs.eigenvalues();
MatrixXcd evecs = eigs.eigenvectors();
/* std::cout << "computed eigenvalues D = \n" << evals.transpose() << std::endl;
std::cout << "first 5 rows of computed eigenvectors U = \n" << evecs.topRows<5>() << std::endl;
std::cout << "nconv = " << nconv << std::endl;
std::cout << "niter = " << niter << std::endl;
std::cout << "nops = " << nops << std::endl;
MatrixXcd err = M * evecs - evecs * evals.asDiagonal();
std::cout << "||AU - UD||_inf = " << err.array().abs().maxCoeff() << std::endl; */
end = get_wall_time();
time_used = (end - start) * 1000;
MatrixXcd err = M * evecs - evecs * evals.asDiagonal();
prec_err = err.cwiseAbs().maxCoeff();
}
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