Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2006
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Evaluating integral with varying upper limit?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg71054] Re: Evaluating integral with varying upper limit?
  • From: "dimitris" <dimmechan at yahoo.com>
  • Date: Wed, 8 Nov 2006 05:59:59 -0500 (EST)
  • References: <eimqg9$b9k$1@smc.vnet.net>

It will be very helpful if you give your function f[x]

Regards
Dimitris

AES wrote:
> Given a function  f[x]  which happens to be rather messy and not
> analytically integrable, I want to evaluate the function
>
>    g[y_] := NIntegrate[f[x], {x, ymin, y} ]
>
> with ymin fixed and  ymin < y < Infinity.
>
> I suppose that FunctionInterpolate is the way to go here (???).
>
> But, are there tricks to tell FunctionInterpolate what I know in
> advance, namely that f[x] is everywhere positive, and decreases toward
> zero rapidly enough at large x that g[y] will approach a finite limiting
> value as y -> Infinity? (which value I'd like to have FI obtain with
> moderate accuracy -- meaning 3 or 4 significant digits, not 10 or 20)
> 
> Thanks . . .


  • Prev by Date: Points sampled by FindMinimum
  • Next by Date: Merge of Matrices
  • Previous by thread: Re: Points sampled by FindMinimum
  • Next by thread: Re: Evaluating integral with varying upper limit?