[Haskell] Literal for Infinity
Lennart Augustsson
lennart at augustsson.net
Sun Oct 2 10:35:02 EDT 2005
Not all FP representations have infinity, and even if
they do, they might only have one infinity.
-- Lennart
Frederik Eaton wrote:
> I've previously mentioned that I would like to see an 'instance
> Bounded Double' etc., as part of the standard, which would use 1/0 for
> maxBound, or the largest possible value (there must be one!) for
> platforms where that is not possible. I don't see a problem with
> looking at Double values as if they were bounded by -infinity and
> +infinity.
>
> On Thu, Sep 29, 2005 at 09:11:25PM +0300, Yitzchak Gale wrote:
>
>>Hi Jacques,
>>
>>Thanks also to you for a most interesting reply.
>>
>>This same discussion has taken place on the
>>discussion list of every modern general-purpose
>>programming language.
>>
>>The same points are always raised and argued, and
>>the conclusion is always the same: floating point
>>exceptions should raise exceptions. Programs that
>>are so sensitive that the tiny overhead makes a
>>difference should use numeric libraries, unboxed
>>types, FFI, and the like.
>>
>>In Haskell also, it looks like the infrastructure
>>was already laid in the Control.Exception module.
>>I hope we will soon be using it.
>>
>>I personally would like also to see alternative
>>functions that return values in the Error monad.
>>
>>Regards,
>>Yitz
>>
>>On Thu, Sep 29, 2005 at 03:13:27PM +0300, Jacques Carette wrote:
>>
>>>The IEEE 754 standard says (fairly clearly) that +1.0 / +0.0 is one of
>>>the most 'stable' definitions of Infinity (in Float at least).
>>>Throwing an exception is also regarded as a possibility in IEEE 754, but
>>>it is expected that that is not the default, as experience shows that
>>>that is a sub-optimal default. Mathematical software (Maple,
>>>Mathematica, Matlab) have generally moved in that direction.
>>>
>>>Almost all hardware implementations of float arithmetic now default to
>>>IEEE 754 arithmetic. Having the arithmetic do 'something else' involves
>>>more CPU cycles, so users should generally complain if their system's
>>>arithmetic differs from IEEE 754 arithmetic without some deep reason to
>>>do so [there are some; read and understand William Kahan's papers for
>>>these].
>>>
>>>Jacques
>>
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