Undoc'd Feature?

[Wes Loewer]

It's hard to trace exactly what is happening in the code without knowing the values in list A, but are you sure that it's actually decrementing?

When I use --X in an HPPL program, or on the Home screen, it is interpreted as -(-X), the negative of the negative of X. Likewise, ---X is -(-(-X)).

In CAS programs (with #cas ... #end), or on the CAS screen, it does allow a++ and a-- but not ++a or --a.

I don't know if this is considered a bug, but in CAS a++ is really doing ++a, incrementing BEFORE evaluating the expression. Likewise for a--. Same behavior in xcas. Maybe it's documented somewhere, but I couldn't find it.