Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

Re: Problems to find the local extrema of an InterpolatingFunction

• To: mathgroup at smc.vnet.net
• Subject: [mg87902] Re: [mg87876] Problems to find the local extrema of an InterpolatingFunction
• From: "W_Craig Carter" <ccarter at mit.edu>
• Date: Sat, 19 Apr 2008 23:49:56 -0400 (EDT)
• References: <200804190734.DAA09779@smc.vnet.net>

Hello Modeler,

I beleive the best strategy for you is:   plot your
InterpolationFunction over its
finite domain, visually look for the roots, and then find them with:
FindRoot[InterpolatingFunction[x],{x,firstguess,leftlimit, rightlimit}]

If you need to do this for many unknown Interpolating functions, then
you will need to automate this a bit---for example by moving the
search domain iteratively.  But, if you only have one, graphically
assisted root finding works well in my experience.
Craig

On Sat, Apr 19, 2008 at 3:34 AM, Modeler <eabad at ulb.ac.be> wrote:
> Hi,
>
>  does anyone know how to find all the local extrema of an InterpolatingFunction in a specified interval? The only
>  thing that seems to work is Findroot, but it only finds a single root each time. Other rootfinding commands do not seem to work. Thanks for your help.
>
>



-- 
W. Craig Carter

• References:
  • Problems to find the local extrema of an InterpolatingFunction
    • From: Modeler <eabad@ulb.ac.be>