Hi Laurent,
On Sat, 23 May 2009 09:04:06 -0700 (PDT)
Laurent Claessens <moky.m...@gmail.com> wrote:
>
> Hello everybody
>
> ----------------------------------------------------------------------
> | Sage Version 3.4.1, Release Date: 2009-04-21 |
> | Type notebook() for the GUI, and license() for information. |
> ----------------------------------------------------------------------
> sage: var('x')
> x
> sage: f=x*cos(x)
> sage: find_minimum_on_interval(f, 1, 10)
> (-3.2883713955908962, 3.4256184628677961)
>
> This is already wrong : the minimum is at -9,...
>
> On fact :
>
> sage: find_minimum_on_interval(f, 8, 10)
> (-9.4772942594797929, 9.5293344182012572)
>
>
> Seems strange that asking maximum on the interval [8,10] returns the
> correct answer that is not found on the interval [1,10].
>
> By the way :
>
> sage: find_minimum_on_interval(f, 1, 15)
> (-9.4772942594797929, 9.5293344109473779)
>
> is correct.
>
> So, the max is at 9, but
>
> [1,10] --> 3 incorrect
> [8,10] --> 9 correct
> [1,15] --> 9 correct
>
> Is there a way to get it correct on the first strike ?
>
> Is it related to the following ?
> sage : find_maximum_on_interval(f, 0, 5)
> TypeError: cannot coerce type '<class
> 'sage.calculus.equations.SymbolicEquation'>' into a
> SymbolicExpression.
>
>
> That question was already raised here, but received no answer :
> Find maximum on interval for result of diff() function.
> http://groups.google.fr/group/sage-support/browse_thread/thread/4ed5ae2b21d6cc6c/03f9d86182655d14?hl=fr?hl=fr&lnk=gst&q=interval#03f9d86182655d14
>
>
>
> Any idea to use correctly find_maximum/minimum_on_interval ?
There are two entries on the bug tracker related to this issue:
http://trac.sagemath.org/sage_trac/ticket/2607
http://trac.sagemath.org/sage_trac/ticket/5960
I believe this would be a fairly easy fix for someone familiar with
knowledge of the relevant scipy methods.
Cheers,
Burcin
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