NIntegrate and replacements

*To*: mathgroup at smc.vnet.net*Subject*: [mg127752] NIntegrate and replacements*From*: S-Tat <kravcov.msu at gmail.com>*Date*: Sat, 18 Aug 2012 03:47:24 -0400 (EDT)*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 everyone, I have a simple question. There is my code, it integrates a function which is a solution of the equation: bc[r_, x_] := r + x^2; sol[r_] := Re[x /. FindRoot[bc[r, x] == 0, {x, 1.1 + I}]]; NIntegrate[sol[r], {r, 1, 8}] Trying this code, I got these messages: FindRoot::nlnum: "The function value {(0.21 +2.2\ I)+r}\\n is not a list of numbers with dimensions {1} at {epseff} = {1.1 +1.` I}" ReplaceAll::reps: "{FindRoot[bc[r,epseff]==0,{epseff,1.1 +I}]}\\n is neither a list of replacement rules nor a valid dispatch table, and so cannot be used for replacing" Sorry if it's too dumb but I cannot see why NIntegrate couldn't just use exact value for r every time. Isn't it how numerical integration is supposed to work? Thank you

**Follow-Ups**:**Re: NIntegrate and replacements***From:*Bob Hanlon <hanlonr357@gmail.com>