pe.cpp

#include "Matrix.h"
#include "Structs.h"


using namespace std;

int main(int argc, char **argv)
{
    //take filename as argument and open
    if (argc != 2)
    {
        std::cout << "Need file name" << std::endl;
        exit(1);
    }
    auto start = std::chrono::high_resolution_clock::now();
    std::ifstream myfile;
    myfile.open(argv[1]);
    if (!myfile.is_open())
    {
        std::cout << "file not opened" << std::endl;
        exit(1);
    }

    //Scan First line containing number of vertices,edges and faces.
    int num_ver, num_edge, num_triangle;
    myfile >> num_ver >> num_edge >> num_triangle;

    //Scan num_ver rows containing coordinates of vertex
    std::vector<std::array<float, 3> > vertices;
    for (int i = 0; i < num_ver; i++)
    {
        std::array<float, 3> buf;
        for (int j = 0; j < 3; j++)
        {
            myfile >> buf[j];
        }
        vertices.push_back(buf);
    }

    //Scan num_edge rows containing vertices that join to form edges
    std::vector<std::array<int, 2> > edges;
    for (int i = 0; i < num_edge; i++)
    {
        std::array<int, 2> buf;
        for (int j = 0; j < 2; j++)
        {
            myfile >> buf[j];
            buf[j]--;
        }
        if (buf[0] > buf[1])
            std::swap(buf[0], buf[1]);
        edges.push_back(buf);
    }

    //Scan num_triangle rows containing edges that join to form triangles(faces)
    std::vector<std::array<int, 3> > triangles;
    for (int i = 0; i < num_triangle; i++)
    {
        std::array<int, 3> buf;
        for (int j = 0; j < 3; j++)
        {
            myfile >> buf[j];
            buf[j]--;
        }
        triangles.push_back(buf);
    }

    boundary_matrix bm = make_boundary(edges, num_ver);
    Matrix matrix(bm.num_rows, bm.num_cols, 0);
    matrix.populate(bm.num_rows, bm.num_cols, bm.mat);

    vector<int> pivots = matrix.get_pivots();
    // matrix.print();

    vector<int> holes0;

    for (int i = 0; i < pivots.size(); i++)
    {
        if (pivots[i] > num_edge - 1)
        {
            holes0.push_back(pivots[i] - num_edge + 1);
        }
    }
    // cout<< "Pivot Columns: "<<endl;
    // for(int i=0;i<pivots.size();i++)
    // {
    //     cout<<"["<<pivots[i]<<"]"<<" ";
    // }
    cout<<endl;
    cout << "Number of 0-Homology Groups Formed: " << holes0.size() << endl;
    cout << "Representative 0 Cycles: " << endl;
    for (int i = 0; i < holes0.size(); i++)
    {
        cout << "{" << holes0[i] << "}"
             << " ";
    }
    cout << endl;

    std::ofstream outdata;
    outdata.open("holes0_buffer.txt"); // opens the file
    if( !outdata ) { // file couldn't be opened
        cout << "Error: holes0_buffer.txt file could not be opened" << endl;
        exit(1);
    }
    for (int i = 0; i < holes0.size(); i++)
    {
        outdata<< holes0[i] << " ";
    }

    auto end = std::chrono::high_resolution_clock::now();
    cout<<endl<<"- Computation of 0-cycles completed"<<endl;

    // std::cout << "Time Taken is = " << std::chrono::duration_cast<std::chrono::seconds>(end - start).count() << std::endl;
}

struct boundary_matrix make_boundary(std::vector<std::array<int, 2> > edges, int num_ver)
{
    boundary_matrix bm = {num_ver, edges.size() + num_ver, new int *[num_ver]};
    for (int i = 0; i < num_ver; i++)
    {
        bm.mat[i] = new int[edges.size() + num_ver];
    }

    for (int i = 0; i < num_ver; i++)
    {
        for (int j = 0; j < edges.size() + num_ver; j++)
        {
            bm.mat[i][j] = 0;
        }
    }

    for (int e = 0; e < edges.size(); e++)
    {
        int vertex0 = edges[e][0];
        int vertex1 = edges[e][1];
        bm.mat[vertex1][e] = 1;
        bm.mat[vertex0][e] = -1;
    }
    int row = 0;
    for (int e = edges.size(); e < edges.size() + num_ver; e++)
    {
        bm.mat[row][e] = 1;
        row++;
    }

    return bm;
}