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

double **inverse(double **matrix, int order) {
  double **inverse = calloc(order, sizeof(double *));
  for (int i = 0; i < order; i++) {
    inverse[i] = calloc(2 * order, sizeof(double));
    inverse[i][order + i] = 1;
    memcpy(inverse[i], matrix[i], order * sizeof(double));
  }

  for (int i = 0; i < order; i++) {
    for (int j = 0; j < order; j++) {
      if (i == j)
        continue;
      double r = inverse[j][i] / inverse[i][i];

      for (int k = 0; k < order * 2; k++)
        inverse[j][k] -= r * inverse[i][k];
    }
  }

  for (int i = 0; i < order; i++) {
    for (int j = 0; j < order; j++)
      inverse[i][j + order] /= inverse[i][i];
  }

  return inverse;
}

int main() {
  const int ORDER = 3;

  double **matrix = malloc(ORDER * sizeof(double *));
  for (int i = 0; i < ORDER; i++)
    matrix[i] = malloc(ORDER * sizeof(double));

  matrix[0][0] = 92, matrix[0][1] = 4.5, matrix[0][2] = 61; // 92x + 4.5y + 61z = 0
  matrix[1][0] = -2, matrix[1][1] = 0, matrix[1][2] = 92387; // -2x + 92387z = 0
  matrix[2][0] = -2, matrix[2][1] = 0, matrix[2][2] = -23; // -2x - 23z = 0

  double **inv = inverse(matrix, ORDER);

  for (int i = 0; i < ORDER; i++) {
    for (int j = 0; j < ORDER; j++)
      printf("%lf ", inv[i][j + ORDER]);
    printf("\n");
    free(inv[i]);
    free(matrix[i]);
  }
  free(inv);
  free(matrix);
}