Re: fix for expt bug

[Ramakrishnan Muthukrishnan <vu3rdd@gmail.com>]

On Wed, Nov 3, 2010 at 11:23 PM, Ramakrishnan Muthukrishnan
<vu3rdd@gmail.com> wrote:
> On Wed, Nov 3, 2010 at 9:52 PM, Mark H Weaver <mhw@netris.org> wrote:
>> Ramakrishnan and others,
>>
>> I just realized that there is a better way to fix these bugs.  We don't
>> need a new top-level case in expt after all.  Instead, we generalize the
>> scm_integer_expt case to support inexact integer exponents.
>>
>> Within that case, if the exponent is an inexact integer, then we make it
>> exact and make the base inexact, and then call scm_integer_expt.
>
> Mark,
>
> Why do we need to convert the base to inexact? is there any problem if
> they are just as it is and we convert only the exponent to exact when
> they are exact?

scheme@(guile-user)> (integer-expt (exact->inexact 3/2) (inexact->exact 4.0))
$17 = 5.0625
scheme@(guile-user)> (integer-expt 3/2 (inexact->exact 4.0))
$18 = 81/16
scheme@(guile-user)> (integer-expt (exact->inexact 3/2) (inexact->exact 4.0))
$19 = 5.0625

We want an output representation in an inexact form. For that reason,
we would want to do exact to inexact conversion of base. Is that
correct?

Mark, I guess your patch solves the problem in a much more efficient way.

thanks
-- 
  Ramakrishnan