Re: infinity and beyond

[christos%astron.com@localhost (Christos Zoulas)]

In article <201111020203.WAA24875%Sparkle.Rodents-Montreal.ORG@localhost>,
Mouse  <mouse%Rodents-Montreal.ORG@localhost> wrote:
>
>Note this is an _IEEE_ float.  A couple of paragraphs earlier:
>
>   Exceptional values usually result from a computation and include plus
>   infinity, minus infinity, NaN, and denormalized numbers. Exceptional
>   values and the representation of zero are associated only with IEEE
>   S_float, T_float, and X_float formats (/FLOAT=IEEE_FLOAT qualifier),
>   not with VAX floating-point formats.
>
>Note "only with IEEE...not with VAX".
>
>> Should we switch to that?
>
>Not on the VAX, I would argue.  It isn't infinity in any useful sense.

Ok, I got confused by the page.

>> Either way, I think that programs expect to be able to do:
>
>>      double x = INFINITY;
>
>> and that is currently broken on the vax.
>
>I think it's a defensible proposition that it _should_ break on the
>VAX, because VAX floating point does not have anything that acts the
>way generally expected by programs that try to manipulate infinities.
>
>The only useful things I can see that that could turn into on the VAX
>are (1) a reserved operand, (2) the largest representable positive
>value, and (3) a compile-time error.

I think it should compile, otherwise we are not going to be able to build
libm/complex/cproj*.c. I will make it HUGE_VAL or something.

christos