Re: [Maxima-discuss] sometimes 1//2 =/= 1/2

[Raymond T. <toy...@gm...>]

On 12/5/25 10:41 AM, Robert Dodier wrote:
> On Fri, Dec 5, 2025 at 4:58 AM Barton Willis via Maxima-discuss
> <max...@li...> wrote:
>> Another thing:  Although bfhalf automatically updates when  fpprec changes, some special variables defined in globals.lisp do not.
> I wonder if any specific bigfloat values should be functions instead
> of constants, so that changing fpprec causes a different value to be
> returned. Or maybe baking the prevailing fpprec into the symbol name,
> something like BIGFLOAT-%PI-FOR-DEFAULT-FPPREC or whatever.
I agree on adding functions.  We already have `fppi` that returns a 
bigfloat pi for the current fpprec. But `fppi` returns a bfloat object 
sans bfloat marker.   And `fppi` is memoized.  I think if you use the 
bigfloat package, you get `(bigfloat:%pi num)` where `num` is only used 
to figure out what kind of result to return (single, double, big 
float).  Similarly for `bigfloat:%e`.
>
> Speaking strictly for myself, I can't keep it straight in my head when
> some constant is no longer valid in some context ... if developers are
> supposed to "just know", then it's likely that I'll mess it up at some
> point. YMMV as always.
I don't think it's just you.