Re: FindRoot cannot find obvious solution

*To*: mathgroup at smc.vnet.net*Subject*: [mg47821] Re: FindRoot cannot find obvious solution*From*: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig-de>*Date*: Wed, 28 Apr 2004 06:56:07 -0400 (EDT)*Organization*: Uni Leipzig*References*: <c6l872$ire$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, and what is with h1 = 1 + (y - x)^2; h2 = 1 + (2/3 - x^2)^2; b = h2/(h1 + h2); f = x(1 - x)^2; s = f*D[b, y]; g[yy_?NumericQ] := NIntegrate[Evaluate[s /. y -> yy], {x, 0, 1}] FindRoot[g[y] == 0, {y, 0.35, 0.45}] Regards Jens "Mukhtar Bekkali" <mbekkali at iastate.edu> schrieb im Newsbeitrag news:c6l872$ire$1 at smc.vnet.net... > Here is my code in Mathematica 5: > > h1=1+(y-x)^2; > h2=1+(2/3-x^2)^2; > b=h2/(h1+h2); > f=x(1-x)^2; > s=f*D[b,y]; > g[y_]:=NIntegrate[s,{x,0,1}]; > FindRoot[g[y]==0,{y,0.35,0.45}] > > The output is > > NIntegrate::inum: Integrand H is not numerical at {x} = {0.5`}. > FindRoot::cvmit: Failed to converge to the requested accuracy or precision > within 100 iteration > > and it gives me y->0.45 or the upper boundary. However, when I plot g[y] I > can see that the solution is somewhere around y=0.4. Using Solve instead of > FindRoot does not give me any solutions. > > What am I doing wrong here? Thank you in advance. Mukhtar Bekkali > >