RE: Simple Eval Question

*To*: mathgroup at smc.vnet.net*Subject*: [mg31953] RE: [mg31883] Simple Eval Question*From*: "Higinio Ramos" <higra at usal.es>*Date*: Fri, 14 Dec 2001 04:21:15 -0500 (EST)*References*: <200112091107.GAA18114@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

----- Original Message ----- From: ivo welch <ivo.welch at anderson.ucla.edu> To: mathgroup at smc.vnet.net Subject: [mg31953] [mg31883] Simple Eval Question > I have a simple problem. I want to numerically solve > > Solve[ Integrate[ f[x,p]*g[x], {x,0,Infinity}] == V , p ] > > where f[] and g[] are defined functions, but the naive solution fails. > > W=1; g=0.5; q=0.1; V=2; > fd[x_]:= PDF[ LogNormalDistribution[0,1],x ] ; > Solve[ Integrate[ ((W +(x-p)*q)^g)/g * fd[x], { x, 0, Infinity } ]== V, p ] > > Solve::"tdep": "The equations appear to involve the variables to be solved \ > for in an essentially non-algebraic way." > > The correct answer seems to be 1.5652 . How do I ask Mathematica to tell me > this number? > > (My ultimate goal is to plot the solved p as a function of q.) > > /iaw > W = 1; g = 0.5; q = 0.1; V = 2; fd[x_] := PDF[ LogNormalDistribution[0, 1], x ] ; In[13]:= SetPrecision[ dRoot[ Integrate[ ((W + (x - p)*q)^g)/g * fd[x], { x, 0, Infinity } ] == V, {p, 1.5} ], 20] Out[13]= {p -> 1.5652055223965051223} H. Ramos

**References**:**Simple Eval Question***From:*ivo.welch@anderson.ucla.edu (ivo welch)