Re: FindRoot s all

*To*: mathgroup at smc.vnet.net*Subject*: [mg49422] Re: FindRoot s all*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Mon, 19 Jul 2004 07:46:12 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 7/18/04 at 8:09 AM, mathma18 at hotmail.com (Narasimham G.L.) wrote: >y[u_,c_]=c^u-u^c-1 ; Plot[y[x,2],{x,-5,5}]; >FindRoot[y[x,2]==0,{x,-5,5}]; " Solution settles to a value outside >the interval of roots of its derivative (humps and valleys),it may >be the problem of Newton-Raphson diverging tangets.How to capture >all roots [in this case {x -> 0, 1}] ? It should be valid for all >c." You didn't say what version of Mathematica you were using. I get $Version "5.0 for Mac OS X (June 10, 2003)" y[u_, c_] = c^u - u^c - 1; FindRoot[y[x, 2] == 0, {x, -5, 5}] {x -> 4.257461914447932} with no error messages To find other roots with FindRoot, simply choose different starting points, i.e. FindRoot[y[x, 2] == 0, {x, 0.5}] {x -> 1.0000000000000004} There is a package written by Ted Ersek availble on the Wolfram web site that is very useful for this type of problem. With it, you can do << "Enhancements`RootSearch`"; RootSearch[y[x, 2] == 0, {x, -5, 5}] {{x -> 0.}, {x -> 1.}, {x -> 4.257461914447932}} and get all the roots at once. -- To reply via email subtract one hundred and four