public function testTranspose()
{
$arr1 = array(array(1, 2), array(3, 4));
$mat1 = new Matrix($arr1);
$t = $mat1->Transpose();
$testarr = array(array(1, 3), array(2, 4));
$this->assertSame($t->GetInnerArray(), $testarr);
}
/**
* Compute the inverse of the matrix on which this method is found (A*A(-1)=I)
* (cofactor(a))T/(det a)
* @link http://www.mathwords.com/i/inverse_of_a_matrix.htm
* @throws \Exception
* @return Matrix
*/
function Inverse()
{
if (!$this->isSquareMatrix()) {
throw new \Exception("Not a square matrix!");
}
$rows = $this->rows;
$columns = $this->columns;
$newMatrix = array();
for ($i = 0; $i < $rows; $i++) {
for ($j = 0; $j < $columns; $j++) {
$subMatrix = $this->GetSubMatrix($i, $j);
if (fmod($i + $j, 2) == 0) {
$newMatrix[$i][$j] = $subMatrix->Determinant();
} else {
$newMatrix[$i][$j] = -$subMatrix->Determinant();
}
}
}
$cofactorMatrix = new Matrix($newMatrix);
return $cofactorMatrix->Transpose()->ScalarDivide($this->Determinant());
}