Typo... of course, I was meaning ratlimit, not ratsimp, anywere I wrote it...
2009/8/25 Stefano Ferri <ferriste at gmail.com>:
> Your comment is rigth, I have no way to check if expression is
> rational in _bk. Anyway, because _bk is only used to impose linear
> dependence conditions on the coefficient matrix, results will be
> rational in _bk. If I am rigth, only integer powers of _bk will
> appear, therefore in this particular case ratsimp is a good solution.
> Only for such expressions ratsimp will be used, so I hope not to be
> wrong to apply it without check the expression.
> For other situations I will use tlimit. But because here I know "a
> priori" that vector of unknowns will be rational in _bk, I think that
> this method is ok, Moreover, ratlimit is only used in internal
> calculations in my program, and users will not use it. It is used
> "under the hood".
>
> I agree with your comment, but I hope it's ok if used in this way. For
> particular situations, 10-20 of such limits will be calculated, and
> ratsimp can greatly improve performances.
>
> Stefano
>
>
>
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> 2009/8/25 Stavros Macrakis <macrakis at alum.mit.edu>:
>> This ratlimit function may be better for this particular case, but I would
>> really hesitate before including it in any code I wrote, because it is too
>> brittle. For example, ratlimit(exp(x)/x,x,inf) will blithely return 0.
>> Years of sad experience shows that code that doesn't check that its
>> arguments are of the correct form will inevitably be called on arguments
>> which are of incorrect form, and return incorrect results with no warning to
>> the user.
>>
>> If tlimit is fast enough for your application, I would stick to it.
>>
>> ??????????????? -s
>>
>