CAS questions: IF...THEN and length() function

[Nigel (UK)]

I've been writing some simple CAS programs in CAS mode and I've encountered a few issues. The first is to do with return:

Code:

#cas
rtest(x):=
BEGIN
IF (x<0) THEN return -1; END;
return 1;
END;
#end

I'd expect this to return -1 if x<0 and 1 otherwise, but it always returns 1. It isn't hard to work around this (using ELSE), but is there something that I'm missing here?

The second issue (rather obscure) is to do with the length() function. length("abc") returns 3, which is fine. length(x+2=y) (note: expressions in XCAS seem to be stored as lists) returns 2, although it has three elements.

More generally: does anyone know where I can find lots of CAS programs written for the Prime? I like to learn a programming language by looking at programs that other people have already written!

Nigel (UK)