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#include "CrsMatrix.h"
#include "LanczosSolver.h"
#include "Matrix.h"
#include "PsimagLite.h"
#include <fstream>
int main(int argc, char** argv)
{
if (argc != 2) {
std::cerr << "Expected filename\n";
return 1;
}
typedef double RealType;
typedef std::complex<RealType> ComplexType;
typedef PsimagLite::ParametersForSolver<double> SolverParametersType;
typedef PsimagLite::Vector<RealType>::Type VectorRealType;
typedef PsimagLite::Vector<ComplexType>::Type VectorType;
PsimagLite::Matrix<ComplexType> m;
std::ifstream fin(argv[1]);
PsimagLite::String file(argv[1]);
if (!fin || fin.bad() || !fin.good())
throw PsimagLite::RuntimeError("Could not open file " + file + "\n");
SizeType tmp = 0;
fin >> tmp;
SizeType n = 1;
fin >> n;
if (tmp != n)
throw PsimagLite::RuntimeError("Matrix in file " + file + " is not square\n");
m.resize(n, n, 0);
for (SizeType i = 0; i < n; ++i)
for (SizeType j = 0; j < n; ++j)
fin >> m(i, j);
PsimagLite::CrsMatrix<ComplexType> msparse(m);
SolverParametersType params;
params.lotaMemory = true;
params.tolerance = -1;
params.options = "reortho";
typedef PsimagLite::LanczosSolver<
SolverParametersType,
PsimagLite::CrsMatrix<ComplexType>,
VectorType>
LanczosSolverType;
LanczosSolverType lanczosSolver(msparse, params);
VectorType initial(n);
PsimagLite::fillRandom(initial);
VectorRealType eigs(n);
PsimagLite::diag(m, eigs, 'V');
std::cout << "\nEXACT: ";
for (SizeType excited = 0; excited < n; ++excited)
std::cout << eigs[excited] << " ";
std::cout << "\n";
std::cout << "LANCZ: ";
LanczosSolverType::VectorVectorType zz;
lanczosSolver.computeAllStatesBelow(eigs, zz, initial, n);
std::cout << "LANCZOS: \n";
for (SizeType excited = 0; excited < n; ++excited) {
std::cout << "<E>_" << excited << " = " << eigs[excited] << " \n";
}
std::cout << "\n";
}
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