fork(1) download
copy 
  1. #include <iostream>
  2.  
  3. double determinant(const double (&M)[2][2]){
  4.     return M[0][0] * M[1][1] - M[0][1] * M[1][0];
  5. }
  6.  
  7. template <std::size_t N>
  8. double determinant(const double (&M)[N][N]){
  9.     double det=0.0;
  10.  
  11.     double Mminor[N - 1][N - 1];
  12.     double sign = 1.0;
  13.     for (int i = 0; i < N; i++) {
  14.         //get the minor matrix
  15.         for (int a = 1; a < N; a++) {
  16.             int m=0;
  17.             for (int b = 0; b < N; b++) {
  18.                 if (b != i) {
  19.                     Mminor[a - 1][m] = M[a][b];
  20.                     m++;
  21.                 }
  22.             }
  23.         }
  24.         //add top row element times determinant of its minor
  25.         det += sign * M[0][i] * determinant(Mminor);
  26.         //swap the sign
  27.         sign *= -1.0;
  28.     }
  29.     return det;
  30. }
  31.  
  32. int main(){
  33.     const double myMatrix[3][3] = {{1,2,3}, {4,5,6}, {3,6,1}};
  34.     double okay = determinant(myMatrix);
  35.     std::cout << "determinant = " << okay << std::endl;
  36. }
Success #stdin #stdout 0s 4392KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
determinant = 24
https://ideone.com/h3U6OA
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!