Extracts a 2x2 matrix from a given matrix and store the result in a FloatArray
a new FloatArray array with 4 elements : the 2x2 matrix extracted from the given matrix
defines the matrix to use
Extracts a 2x2 matrix from a given matrix and store the result in a FloatArray
Returns
a new FloatArray array with 4 elements : the 2x2 matrix extracted from the given matrix