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 include in your email, then within the *Cell* menu select either *Convert To* or *Display As* and choose *InputForm*. Finally, copy and paste as usual.