Re: Will Integrate ever finish?
- To: mathgroup at smc.vnet.net
- Subject: [mg23632] Re: [mg23622] Will Integrate ever finish?
- From: "Mark Harder" <harderm at ucs.orst.edu>
- Date: Thu, 25 May 2000 01:00:43 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
>I don't know if Integrate will solve my function. The most general form is > >Integrate[1/(1+a*x+b*Sqrt[c-x^2])^(3/2),x] > I don't know, either. It looks difficult to me. Can't help you here. >It has been running for over a day and I don't know if it will ever resolve. >Is it possible that Integrate will go into some infinite loop and never >stop, ...? You bet it can. If you're using a reasonably modern system, equivalent roughly to a Pentium or better, my guess is that there's probably no solution Mathematica can still be making progress in 24 hrs. Even if it can, I would rather spend my time looking up the answer in a good table of integrals or trying to transform the problem by hand. Better to limit the time on problems like this with the TimeConstrained function. I gave the problem a little over 3 min.: In:= TimeConstrained[Integrate[(1 + a*x + b*Sqrt[c - x^2])^(-3/2), x], 200.] Out= $Aborted Other related things: Mathematica can take significant time preparing printed output. If you suspect that your answer will be a long one, better to assign it to a variable and suppress printing, then print out the answer after you know there is an answer. In earlier versions of Mathematica, the Abort command (in the Kernel menu) didn't always work, or was very slow in itself. When I went from v3.0 to 4.0, I noticed a very significant improvement in Abort, one of the things about 4.0 I am very pleased about. -mark