getW method
Gets w
dimension of a flat index (see flatten).
Implementation
int getW(int i) {
if (i < 0 || i >= numberOfElements) {
throw ArgumentError.value(i);
}
final w = this.w;
if (w == 0) {
throw StateError('No `w` index');
}
return (i ~/ (x * y * z)) % w;
}