/**
* Divides one mapping by another.
*
* <p>{@code divide(A, B)} returns a mapping C such that B . C (the mapping B followed by the
* mapping C) is equivalent to A.
*
* @param mapping1 First mapping
* @param mapping2 Second mapping
* @return Mapping mapping3 such that mapping1 = mapping2 . mapping3
*/
public static Mapping divide(Mapping mapping1, Mapping mapping2) {
if (mapping1.getSourceCount() != mapping2.getSourceCount()) {
throw new IllegalArgumentException();
}
Mapping remaining =
create(
MappingType.INVERSE_SURJECTION, mapping2.getTargetCount(), mapping1.getTargetCount());
for (int target = 0; target < mapping1.getTargetCount(); ++target) {
int source = mapping1.getSourceOpt(target);
if (source >= 0) {
int x = mapping2.getTarget(source);
remaining.set(x, target);
}
}
return remaining;
}
public int getTargetOpt(int source) {
return parent.getSourceOpt(source);
}