On Fri, May 1, 2009 at 8:05 PM, William Stein <wst...@gmail.com> wrote:
>
> On Fri, May 1, 2009 at 4:58 PM, Thomas Savitsky <tjsavit...@gmail.com> wrote:
> > Hello all,
> >
> > I've noticed that the function find_minimum_on_interval makes no attempt to
> > find "the" minimum on the interval as the documentation implies, but rather
> > "a local" minimum.  I imagine this may be a source of confusion for other
> > new users as well.  Rather than treating this as a bug, may I suggest
> > changing the documentation for this function to reflect that it only finds a
> > local minimum and adding an additional function which searches for a global
> > minimum?
>
> +1  Can you provide a few examples for the docstring that illustrate this?

Do these work?

sage: h(x) =  -sin(x) - 2*sin(2*x)
sage: h.find_minimum_on_interval(0, 2*pi)
(-1.3271810224585345, 3.8298351449342838)
But there is another local minimum at h(0.8666760871050464) = -2.73581510406


sage: find_minimum_on_interval(x*(x-1)*(x+1), -2, 2)
(-0.38490017945975047, 0.57735026913115706)
The minimum on this interval is the endpoint h(-2) = 6.


sage: find_minimum_on_interval((x-2)*(x-1)*x*(x+1) - x, -2, 2)
(-0.43749999999999994, -0.49999999973911674)

but
sage: find_minimum_on_interval((x-2)*(x-1)*x*(x+1) - x, 0, 2)
(-2.6642135623730949, 1.7071067879138031)

--Thomas

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