Question

How to calculate the determinant of a 3X3 matrix in C++

Answer 1

#include <iostream>
#include <iomanip>

#define SIZE 3

using namespace std;

int main()
{
	
	float arr[SIZE][SIZE] = { { 6, 1, 1 },{ 4, -2, 5 },{ 2, 8, 7 } };

	/*
	*       a b c
	* arr = d e f
	*       g h i
	*
	* determinant = a*(e*i - f*h) - b*(d*i-f*g) + c*(d*h - e*g)
	*
	*/

	float determinant = arr[0][0] * (arr[1][1] * arr[2][2] - arr[1][2] * arr[2][1]) -
		                arr[0][1] * (arr[1][0] * arr[2][2] - arr[1][2] * arr[2][0]) +
		                arr[0][2] * (arr[1][0] * arr[2][1] - arr[1][1] * arr[2][0]);
	
	
	cout << fixed << setprecision(2) << determinant << endl;

	return 0;
}


/*
run:

-306.00

*/

 

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