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Re: Find all roots with FindRoot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg126153] Re: Find all roots with FindRoot
  • From: "djmpark" <djmpark at comcast.net>
  • Date: Sat, 21 Apr 2012 00:31:01 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <25227796.28036.1334923020612.JavaMail.root@m06>

You might try Ted Ersek's RootSearch package. This returns all real roots
within an interval in order. Although this is a common usage, and some
combination of FindRoot, Solve or Reduce will sometimes suffice, there
doesn't seem to be a common Mathematica routine that is as convenient and
easy as Ted's routine. Ted's routine will also find zeros that do not cross
the axis, and I seem to recall it can be used to find roots defined on
curves defined by a single parameter.

http://library.wolfram.com/infocenter/MathSource/4482/ 


David Park
djmpark at comcast.net 
http://home.comcast.net/~djmpark/index.html 




From: Sam Takoy [mailto:sam.takoy at yahoo.com] 


Hi,

I need to find all roots of a function in a certain interval. FindRoot only
finds one. I imagine that I could write a script that calls FindRoot
repeatedly, but I'm guessing this must be built-in functionality or someone
has written such a script in the past (better than I ever could).

Can someone direct me to a command or a script like that?

Many thanks in advance,

Sam




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