Nijso Beishuizen <nijso at hotmail.com> writes:
> I sometimes get as an intermediate solution of a calculation
> atan2(0,x).
>
> When x:5, then trigreduce knows that atan2(0,5) = 0, but when x is
> defined as a constant or nothing is assumed on x, then atan2 stays.
>
> I don't speak lisp, but I think the simplification atan2(0,x)=0 can be
> done by adding something in comm2.lisp?
Well,
(%i1) atan2(0,-1);
(%o1) %pi
(%i2) atan2(0,1);
(%o2) 0
(%i3) atan2(0,0);
atan2: atan2(0,0) is undefined.
-- an error. To debug this try: debugmode(true);
Moreover Maxima is pretty clever here, it seems:
(%i4) assume(x > 0)$
(%i5) atan2(0,x);
(%o5) 0
(%i6) forget(x > 0)$ assume (x < 0)$
(%i8) atan2(0,x);
(%o8) %pi
Rupert
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