"

As a rule of thumb, one can say that 0^0 = 1 , but 0.0^(0.0) is

undefined, meaning that when approaching from a different direction

there is no clearly predetermined value to assign to 0.0^(0.0) ; but

Kahan has argued that 0.0^(0.0) should be 1, because if f(x), g(x) -->

0 as x approaches some limit, and f(x) and g(x) are analytic

functions, then f(x)^g(x) --> 1

"

so it seems that error comes due to the undefined result of 0.0^0.0. Maybe there is some article devoted to this case? I have just implemented the EXPT patch for SBCL, but I do not know what should I return: 1, 1.0 or raise an error?

Regards,

Roman

so it seems that error comes due to the undefined result of 0.0^0.0. Maybe there is some article devoted to this case? I have just implemented the EXPT patch for SBCL, but I do not know what should I return: 1, 1.0 or raise an error?

Regards,

Roman

2010/4/29 Malcolm Reynolds <malcolm.reynolds@gmail.com>

I'm not sure about the Lisp standard's view on this, but here is a

variety of reasons why the correct mathematical answer is (arguably)

1, for any combination of integers or floats. I guess this doesn't

answer whether it should be 1.0 or 1 but it definitely shouldn't be an

error.

http://www.faqs.org/faqs/sci-math-faq/specialnumbers/0to0/

Malcolm

> ------------------------------------------------------------------------------

On Thu, Apr 29, 2010 at 9:01 PM, Roman Marynchak

<roman.marynchak@gmail.com> wrote:

> Hello,

>

> I have found a tricky issue with EXPT behaviour in different

> implementations.

>

> Namely, evaluating (expt 0.0 0) yields:

>

> 1.0 in SBCL

> 1 in CLISP

> 1.0 in Lispworks.

>

> (expt 0 0.0) results in:

>

> 1.0 in SBCL

> error in CLISP

> error in Lispworks

>

>

> CLHS says that 0^0 = 1, and gives no details about float/integer

> combinations of these zeros.

>

> So, what is the valid answer here? Is there some complex math theory behind

> all this?

>

>

> Regards,

> Roman

>

>

> _______________________________________________

> Sbcl-devel mailing list

> Sbcl-devel@lists.sourceforge.net

> https://lists.sourceforge.net/lists/listinfo/sbcl-devel

>

>