Re: Building current...

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>>> Unfortunately, this is one of those places where the VAX not doing IEEE FP$

(Please don't use paragraph-length lines.)

Well, bites people who blindly assume floating point is IEEE.

>> Why not simply fix the bug?  log(0) is invalid.  [...]

Mathematically, it is undefined (for the reals->reals log, at least),
but lim(x->0+) log(x) is minus infinity (in the usual sense in which a
limit is said to be an infinity), so it is not unreasonable to return
-inf for log(0).

> Yes, except I suspect that people are happy just to write the code
> that way, as IEEE FP actually "can deal with it".  log(0) indeed do
> not give a valid value, and the IEEE version indeed returns an
> invalid value.

In what sense?  In IEEE floating point, infinities are not invalid in
any sense as far as I can tell.

> I can't really go around and start fixing all the code people write
> to change the logic... :-/

We fix _other_ bugs; unless the code is actually intended to depend on
having IEEE floats available (which I gather is unlikely to be the case
here), asking for the logarithm of zero is a bug and IMO should be
fixed like any other bug.

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