#2607: find_minimum_on_interval() uses the wrong scipy function
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Reporter: AlexGhitza | Owner: jwmerrill
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.1
Component: calculus | Resolution:
Keywords: sd31, sd40.5 | Work issues:
Report Upstream: N/A | Reviewers: Karl-Dieter Crisman
Authors: Dan Drake | Merged in:
Dependencies: | Stopgaps:
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Description changed by ddrake:
Old description:
> This was reported by Dean Moore on sage-support. Consider:
>
> {{{
> sage: f(x) = -x*sin(x^2)
> sage: f.find_minimum_on_interval(-2.5, 2)
> (-1.3076194129914434, 1.35521114057)
> sage: f.find_minimum_on_interval(-2.5, -1)
> (-2.1827697846777219, -2.19450274985)
> }}}
>
> So find_minimum_on_interval() returns a local minimum as opposed to the
> global one. (The same issue applies to find_maximum_on_interval.) This
> is due to the fact that the function wraps scipy.optimize.fminbound,
> which is only a local optimizer (Carl Witty pointed this out). We should
> instead use one of the global optimizers, i.e. scipy.optimize.anneal or
> scipy.optimize.brute.
New description:
This was reported by Dean Moore on sage-support. Consider:
{{{
sage: f(x) = -x*sin(x^2)
sage: f.find_minimum_on_interval(-2.5, 2)
(-1.3076194129914434, 1.35521114057)
sage: f.find_minimum_on_interval(-2.5, -1)
(-2.1827697846777219, -2.19450274985)
}}}
So find_minimum_on_interval() returns a local minimum as opposed to the
global one. (The same issue applies to find_maximum_on_interval.) This
is due to the fact that the function wraps scipy.optimize.fminbound, which
is only a local optimizer (Carl Witty pointed this out). We should
instead use one of the global optimizers, i.e. scipy.optimize.anneal or
scipy.optimize.brute.
Apply trac2607.patch and trac2607-whitespace.patch
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/2607#comment:20>
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