diagonal method
Returns a mutable diagonal Vector of this Matrix. Throws a
RangeError, if offset
is out of bounds. An offset of 0
refers to the
diagonal in the center of the matrix, a negative offset to the diagonals
above, and a positive offset to the diagonals below.
Implementation
Vector<T> diagonal([int offset = 0]) {
RangeError.checkValueInInterval(
offset, -colCount + 1, rowCount - 1, 'offset');
return diagonalUnchecked(offset);
}