pure-lang-users

Re: [pure-lang-users] Yet another quirk with MinGW

[John C. <co...@cc...>]

Eddie Rucker scripsit:

> Most of the time I'd agree, but I still think log 0 => -inf sucks big
> time. 

You have to remember what -inf and 0.0 actually mean: respectively
"a negative number too small to represent" and "a positive number too
close to zero to represent."  And indeed, if you take the log of a number
too close to zero to represent, such as 1/(10^10^10) you will indeed
get a number too small to represent.

> different from saying log 0 == -inf. That's like saying 9/0 = inf
> because lim 9/x -> inf as x -> 0.

9/0 is indeed inf, though 9%0 ought to be an error (in Q it's inf).

-- 
Even a refrigerator can conform to the XML      John Cowan
Infoset, as long as it has a door sticker       co...@cc...
saying "No information items inside".           http://www.ccil.org/~cowan
        --Eve Maler

Re: [pure-lang-users] Yet another quirk with MinGW

[Albert G. <Dr....@t-...>]

John Cowan wrote:
> 9/0 is indeed inf, though 9%0 ought to be an error (in Q it's inf).

Not so in Pure, it raises a 'signal SIGFPE' exception there (as does 9 
div 0).

I agree that the way this case is implemented in Q just doesn't make any 
sense.

Albert

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikinformatik.uni-mainz.de/ag

Re: [pure-lang-users] Yet another quirk with MinGW

[John C. <co...@cc...>]

Eddie Rucker scripsit:

> You are right for 0.0. Yep, we have to use the |a-b| < epsilon
> definition for equality. However, for the integer 0 and the rational 0%
> 1, shouldn't log 0 be undefined?

Well, in general all the trig functions first cast their argument to a float;
I think everyone expects that in whatever language, though some do provide
integer square root functions, probably because they're easy to implement.

-- 
John Cowan                              <co...@cc...>
            http://www.ccil.org/~cowan
                .e'osai ko sarji la lojban.
                Please support Lojban!          http://www.lojban.org

Re: [pure-lang-users] Yet another quirk with MinGW

[Eddie R. <er...@bm...>]

On Wed, 2008-08-20 at 13:38 -0400, John Cowan wrote:
> Eddie Rucker scripsit:
> 
> > You are right for 0.0. Yep, we have to use the |a-b| < epsilon
> > definition for equality. However, for the integer 0 and the rational 0%
> > 1, shouldn't log 0 be undefined?
> 
> Well, in general all the trig functions first cast their argument to a float;
> I think everyone expects that in whatever language, though some do provide
> integer square root functions, probably because they're easy to implement.
> 

Ok. I can live with that. 

I another note, mz-scheme says (log 0) is undefined and (log 0.0) is
-inf.0. IOW, It really does the right thing.

e.r.

Re: [pure-lang-users] Yet another quirk with MinGW

[Albert G. <Dr....@t-...>]

John Cowan wrote:
> Eddie Rucker scripsit:
> 
>> You are right for 0.0. Yep, we have to use the |a-b| < epsilon
>> definition for equality. However, for the integer 0 and the rational 0%
>> 1, shouldn't log 0 be undefined?
> 
> Well, in general all the trig functions first cast their argument to a float;

Exactly.

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikinformatik.uni-mainz.de/ag