PO1 | Wyznacznik

#include <stdio.h>
#include <stdlib.h>

double det(double **, int);
double ** matrix_alloc( int );
void matrix_free( double** , int);

int main()
{
    FILE* plik;
    if ((plik = fopen("mat5.txt", "r")) == NULL)
        printf("blad z otwarciem pliku");

    int N = -1;
    fscanf(plik, "%d\n", &N);
    printf("%d\n", N);

    double** tab = matrix_alloc(N);

    for (int i = 0; i < N; i++){
        for (int j = 0; j < N; j++){
            fscanf(plik, "%lf ", &tab[i][j]);
        }
        fscanf(plik, "\n");
    }

    fclose(plik);

    for (int i = 0; i < N; i++){
        for (int j = 0; j < N; j++){
            printf("%.2lf    \t", tab[i][j]);
        }
        printf("\n");
    }

    printf("Wyznacznik wynosi: %f", det((double**)tab, N));

    matrix_free(tab, N);
    getchar();
    return 0;
}

double ** matrix_alloc( int N ){
    double **tab = (double**)malloc(sizeof(double*) * N);
    for (int i = 0; i < N; i++)
        tab[i] = (double*)malloc(sizeof(double) * N);

    return tab;
}


void matrix_free (double ** tab, int N){
    for (int i = 0; i < N; i++)
        free(tab[i]);

    free(tab);
}

double det(double ** matrix, int n)
{
    double** minor;
    double sum = 0.0;
    double sign = 1.0;
    int i;

    if (n == 1) return matrix[n-1][n-1];
    if (n == 2) return matrix[n - 1 - 1][n - 1 - 1] * matrix[n - 1][n - 1] - matrix[n - 1][n - 1 - 1] * matrix[n - 1 - 1][n - 1];

    minor = matrix_alloc(n-1);

    for (i = 0; i < n; i++)
    {
        for (register int k = 1, mi = 0; k < n; k++, mi++)
        {
            for (register int j = 0, mj = 0; j < n; j++, mj++)
            {
                if (j == i) mj--;
                else minor[mi][mj] = matrix[k][j];
            }
        }
    }

    sum += sign * matrix[0][i] * det(minor,n-1);

    sign = -sign;

    matrix_free(minor,n-1);
    return sum;
}