testy.cpp

#include <iostream>
#include <cstdlib>
#include <iomanip>

using namespace std;

void printmatrix(float A[][4]);
void RowReduce(float A[][4]);

int main()
{
    float A[3][4] = {{5, -6, -7,   7},
                     {3, -2,  5, -17},
                     {2,  4, -3,  29}}; //answer should be {2, 4, -3}

    printmatrix(A);
    RowReduce(A);
}

void printmatrix(float A[][4]) // Outputs the matrix
{
    int p=3;
    int q=4;

    for (int i=0; i<p; i++) {
            for (int j=0; j<q; j++) {
                    cout << setw(7) << setprecision(4) << A[i][j] << " ";
            }
            cout << endl;
    }

    cout << endl;
}

void RowReduce(float A[][4])
{
  int n=3;
    const int nrows = n; // number of rows
    const int ncols = n+1; // number of columns

    // int lead = 0;

    // while (lead < nrows) {
    for (int lead=0; lead<nrows; lead++)
    {
        float d, m;

        for (int r = 0; r < nrows; r++) { // for each row ...
            /* calculate divisor and multiplier */
            d = A[lead][lead];
            m = A[r][lead] / A[lead][lead];

            for (int c = 0; c < ncols; c++) { // for each column ...
                if (r == lead)
                    A[r][c] /= d;               // make pivot = 1
                else
                    A[r][c] -= A[lead][c] * m;  // make other = 0
            }
        }

        // lead++;
        // printmatrix(A);
    }
}