NIntegrate and Delayed Functions
- To: mathgroup at smc.vnet.net
- Subject: [mg44121] NIntegrate and Delayed Functions
- From: "Mukhtar Bekkali" <mbekkali at hotmail.com>
- Date: Thu, 23 Oct 2003 07:15:30 -0400 (EDT)
- Organization: Iowa State University
- Sender: owner-wri-mathgroup at wolfram.com
Hi all:
I have a function f[x,t] which does not have an explicit integral over t,
only numerical integral exists. Suppose F[x] is an integral of f[x,t] over
t where t ranges from 0 to some function r[x]. I need to plot F'[x] or the
first derivative of F[x] as a function of x (let's call it G[x]). I tried
to use Integrate but Mathematica cannot handle it for some functional forms
of f[x,t] so I am trying to use NIntegrate as a delayed function to speed up
the evaluation. However, I receive an error message that the limit of
integration cannot be z[x] and an empty graph. Here is the exerpt from my
code:
G[x_]:=D[NIntegrate[f[x,t],{t,0,z[x]}],x];
Plot[G[x],{x,0,1}]
What am I doing wrong? Of course all functions,- f[x,t], z[x] have a
specific form.