How to speed up FindRoot with Map or MapThread

*To*: mathgroup at smc.vnet.net*Subject*: [mg129355] How to speed up FindRoot with Map or MapThread*From*: o.sandig at googlemail.com*Date*: Mon, 7 Jan 2013 00:39:14 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

Hi, I would like to speed up FindRoot. In this special case I'm looking for roots of the equation sin[2*theta]+2*h*sin[theta - phi] for different h's and phi's. To do this I specify for each h the region within which the solution has to be found: X = {x_middle, x_left, x_right}, e.g.: FindRoot[sin[2*theta] + 2*h1*sin[theta - phi1] == 0 , {theta, x_middle, x_left, x_right}] That means that h is an mx1 matrix and X is an nx3 matrix (X = {x_middle, x_left, x_right}). The question: How can I use Map or MapThread to combine each element of h with the whole matrix X inside FindRoot to speed it up? Thanks for any idea.

**Follow-Ups**:**Re: How to speed up FindRoot with Map or MapThread***From:*Bob Hanlon <hanlonr357@gmail.com>