main.cpp

#include <iostream>
#include "algebra.hpp"
#include <complex>
#include "chrono.hpp"

int main(){

    //operations with the matrix imported from MatrixMarket and comparison between compressed and
    //uncompressed state multiplication with a vector of random values between 0 and 10
    //the column vector is stored as a 131x1 matrix, we could also have used a normal std::vector
    //by using the function algebra::generate_vector().
    //You can also easily check the column_wise case by changing the declaration of M
    std::cout << "Multiplication operation: comparison between compressed and uncompressed case:" << std::endl;
    Timings::Chrono clock;
    algebra::Matrix<double, algebra::row_wise> M;
    M.read("lnsp_131.mtx");
    algebra::Matrix<double, algebra::row_wise> v= algebra::generate_column_vector<double, algebra::row_wise>(131,0,10);
    //v.print();

    clock.start();
    auto a=M*v;
    clock.stop();
    //algebra::print(a);
    double t1=clock.wallTime();
    std::cout << "Uncompressed matrix: " << clock;
 
    M.compress();
    clock.start();
    auto b=M*v;
    clock.stop();
    //algebra::print(b);
    double t2=clock.wallTime();
    std::cout << "Compressed matrix: " << clock;

    std::cout << "Compressed multiplication is " << t1/t2 << " times faster!" << std::endl << std::endl;

    double normM = M.norm<algebra::frobenius>();
    std::cout << "Frobenius norm of M: " << normM << std::endl;

    M.uncompress();

    //Everything works also with complex numbers! Below I provide a simple example, you can uncomment
    //the output lines to check the results:

    std::complex<double> z1(0,3);
    std::complex<double> z2(2,1);
    std::complex<double> z3(5,4);
    std::complex<double> z4(1,3);
    std::complex<double> z0(0,0);

    algebra::Matrix<std::complex<double>, algebra::column_wise> N({{z1, z0, z0}, {z2, z0, z3}, {z0, z0, z2}});
    N(2,1)=z4;
    //N.print();
    //double normN = N.norm<algebra::infinity>();
    //std::cout << "Infinity norm of the matrix: " << normN << std::endl;
    std::vector<std::complex<double>> v2({z1, z3, z4});
    //algebra::print(v2);
    auto c=N*v2;
    //algebra::print(c);
    N.compress();
    //N.print();
    N.uncompress();
    //N.print(); 

}