[SciPy-Dev] Doc error in scipy.optimize.fmin and missing info in ref guide
Fri Mar 19 15:09:57 CDT 2010
On Fri, Mar 19, 2010 at 4:05 PM, David Goldsmith
> On Fri, Mar 19, 2010 at 12:37 PM, <email@example.com> wrote:
>> On Fri, Mar 19, 2010 at 3:16 PM, David Goldsmith
>> <firstname.lastname@example.org> wrote:
>>> On Mon, Mar 15, 2010 at 4:05 PM, Rob Clewley <email@example.com> wrote:
>>>> In both my old version and the one in the svn trunk there is an
>>>> inconsistency in the docstring of scipy.optimize.fmin.
>>>> Other Parameters
>>>> xtol : float
>>>> Relative error in xopt acceptable for convergence.
>>>> ftol : number
>>>> Relative error in func(xopt) acceptable for convergence.
>>>> As you see from the following code snippet from the body of the
>>>> function, the convergence test is in terms of absolute error for both
>>>> x and f, as the sim array contains x values and fsim the function
>>>> if (max(numpy.ravel(abs(sim[1:]-sim))) <= xtol \
>>>> and max(abs(fsim-fsim[1:])) <= ftol):
>>> OK, folks, so what's the _desired_ behavior: absolute or relative
>>> error (i.e., where's the bug: in the code or in the doc)?
>> I think the docs should reflect the actual behavior of the function.
>> Whether the criteria will be changed and made consistent across
>> functions is a different question. But it's not a bug, so the docs
>> should adjust.
>> my opinion
> Well, I'm pretty sure we formally adopted the opposite policy: the
> docs should reflect _desired_ behavior - if the code doesn't implement
> desired behavior then a bug report is to be filed. (I thought this
> was in the Wiki Q&A section, but apparently not, so, UIAM, it's "only"
> in an email thread somewhere). Can anyone else confirm and,
> hopefully, supply a link to the email thread in which this was
I know of that policy, but there are a lot of mistakes in the docs,
and I don't think we change the code to match the mistakes in the
But you can also file a ticket for changing and reviewing convergence criteria
I don't think relative (to what?) error makes much sense if x or f goes to zero.
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