Re: [Maxima-discuss] makelist, map (and probably others) returning unsimplified lists -> extra simplifier calls

[David S. <d.s...@go...>]

Richard Fateman <fa...@gm...>:

> If you  type a command to Maxima,  say f(a,b), defined by f(x,y):= ....
> stuff;
>  then the top-level  read-eval-print loop
> evaluates (and simplifies) a,  then b,  and then applies f to these
> arguments.
>

I think there's another Maxima bug exactly in this step.

Do :lisp (trace simplifya) to see all simplifier calls, then type something
like your example:

atan2(a, b);

You'll see that Maxima first simplifies $A, $B and then ((%ATAN2) $A $B).
But when simplifying the atan2, the second argument to SIMPLIFYA is NIL.
That means "the arguments are not simplified". But it just simplified them!
The result is that $A and $B are simplified a second time.

It becomes even more evident when doing something like atan2(sin(x),
cos(x)) because you'll see that %SIN and %COS already have the SIMP flag,
yet Maxima tells the simplifier that they're not simplified.

Is this indeed a bug, or is there some obscure case where this is necessary?

Best regards
David Scherfgen

>