SqMatrix SqMatrix::inverse() const {
/* Reference: https://chi3x10.wordpress.com/2008/05/28/calculate-matrix-inversion-in-c/ */
SqMatrix inv(order);
double det = determinant();
for (int i=0; i<order; i++) {
for (int j=0; j<order; j++) {
inv.arr[j][i] = minorMat(i,j).determinant() * ((i+j)%2 == 1 ? -1.0 : 1.0) / det;
}
}
return inv;
}
//A bad revursive implementation of diagnol minor, a better way could be using permutations/combinations to select the
//rows/columns
cplxnum CplxMatrix::diagonalMinor(int level) const{
cplxnum result;
if (r != c) {
std::cout<<"incompatible shapes"<<std::endl;
return cplxnum();
}
if (level <= 0) {
std::cout<<"invalid level specification"<<std::endl;
return result;
}
if (level == 1) {
for (int i = 0; i < r; i++) {
result = result + minor(i, i);
}
return result;
}
for (int i = 0; i < r; i++) {
result = result + (1/double(level))*minorMat(i, i).diagonalMinor(level - 1);
}
return result;
}
cplxnum CplxMatrix::minor(int row, int col) const{
return minorMat(row, col).det();
}
//recursive call for permenant, ignoring the signs for det
cplxnum CplxMatrix::subperm(int row, int col) const{
return minorMat(row, col).perm();
}
double Matrix::minor(int row, int col) const{
return minorMat(row, col).det();
}
