Calculate Cofactors, Minors, and value of Determinant of Matrix

Description

This piece of code calculates the cofactors, the minors, and the value of the determinant of a 3x3 matrix with just one line of code each within a loop! Can't make it any shorter!

More Info

matrix[3][3] - containg the values of the matrix

cofactor[3][3] - containing the value of cofactors corresponding to the values in matrix array.

minor[3][3] - containing the value of minors

determinant - containing the value of the determinant.

Submitted On
By	N/A
Level	Beginner
User Rating	3.7 (22 globes from 6 users)
Compatibility	C, C++ (general)
Category	Math
World	C / C++
Archive File

Source Code

/*	The author of this piece of code is Rahul Khanna
	<rahulk@techie.com>
	Use this code at your own risk.
*/
/*	This piece of code demonstrates how you can calculate
	the cofactors, minors and the value of a 3x3 determinant
	itself with the smallest possible code. The cofactor, and
	minors are calculated in one line of code each! Can you
	make it any smaller?
*/
/*	Assuming there is an array "matrix[3][3]" that contains
	the values of the matrix in the format rows x columns.
	The cofactors of the repective matrix element is stored
	in its position values in the array "cofactor". Eg, cofactor
	of array element matrix[1][1] will be stored in cofactor[1][1].
	Same as above with minors.
*/
long row, col;
long matrix[3][3];
long cofactor[3][3], minor[3][3];
long determinant = 0;
for (row = 0; row < 3; row++)
{
	for (col = 0; col < 3; col++)
	{
		cofactor[row][col] = matrix[(row + 1) % 3][(col + 1) % 3] * matrix[(row + 2) % 3][(col + 2) % 3] - matrix[(row + 1) % 3][(col + 2) % 3] * matrix[(row + 2) % 3][(col + 1) % 3];
		minor[row][col] = (row + col) % 2 == 0 ? cofactor : -cofactor;
		if (row == 0)
			determinant += matrix[0][col] * cofactor;
	}
}