Re: Integral problem

• To: mathgroup at smc.vnet.net
• Subject: [mg58317] Re: Integral problem
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Tue, 28 Jun 2005 05:13:16 -0400 (EDT)
• Organization: The Open University, Milton Keynes, England
• References: <d9num6\$cl5\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```HUAFANG CUI wrote:
> Hi,
>
> I have a question about integral.  I could not figure out what is wrong.
>
> function is
> 0.5 * (1 + 10^7 * ((1-x-y)/1.5 + x/8)^10) + 0.004 * x / ((1-x-y)/1.5 +
> x/8)^10)
>
> limit on y is
> 0.8425 - x, 0.8
>
> limit on x is
> 0.0425, 0.1999
>
> I run it on Ver4.0.  It runs forever and does not stop.
>
> Thank you.
>
> HC
>
Hi HC,

Assuming that I have made no mistake in copying your function, although
it does not take forever to integrate it, Mathematica consumes a good
deal of CPU time before displaying the result:

In[1]:=
Timing[Integrate[
0.5*(1 + 10^7*((1 - x - y)/1.5 + x/8)^10) +
0.004*(x/((1 - x - y)/1.5 + x/8)^10),
{x, 0.0425, 0.1999}, {y, 0.8425 - x, 0.8}]]

Out[1]=
{379.906*Second, 1.91538522742034*^8}

(Tested on a Pentium IV 2.6GHz 512Mo Physical Ram, Windows XP SP2,
Mathematica 5.1.)

Best regards,
/J.M.

P.S. You should use the _InputForm_ when copying an expression from a
Mathematica notebook to an email client: select the cell(s) you want to