Re: Integrate vs NIntegrate

*To*: mathgroup at smc.vnet.net*Subject*: [mg89158] Re: [mg89129] Integrate vs NIntegrate*From*: "W_Craig Carter" <ccarter at mit.edu>*Date*: Tue, 27 May 2008 07:16:06 -0400 (EDT)*References*: <200805261023.GAA15126@smc.vnet.net>

Hello Armen, Here are a few changes to your code: q = -1/2; a = 0; b = 3; h[x_] := (1 + x^3)^q (* delayed evaluation := *) f[x_] := Integrate[h[z], {z, 0, x}]; (*z is an integration variable... the integration is a function of its limits*) Res1 = N[f[b] - f[a]] Res2 = NIntegrate[h[x], {x, a, b}] Craig On Mon, May 26, 2008 at 6:23 AM, Armen Kocharyan <armen.kocharyan at gmail.com> wrote: > Why do I get different results (Res1, Res2) in Mathematica 6.0.1.0? > *q=-1/2; a=0; b=3;* > *h[x_]=(1+x^3)^q;* > *f[x_]=Integrate[h[x],x];* > *Res1=N[f[b]-f[a]]* > *Res2=NIntegrate[h[x],{x,a,b}]* -- W. Craig Carter

**References**:**Integrate vs NIntegrate***From:*"Armen Kocharyan" <armen.kocharyan@gmail.com>