MaplePrimes - answers and comments on Question, How to compute an integral of a complicated function of different variables?

Function

Robert Israel — Wed, 30 Nov 2011 12:03:51 Z

This is what functions are for. Try:

> A:= (r,z) -> int( f(r,z, teta), teta=0..0.78);

Then, for example,

A(2,3);

Thanks a lot for your answer, it

sara_ph — Sun, 04 Dec 2011 14:00:11 Z

Thanks a lot for your answer, it works..

I wanted to find an answer for the integral in the form of function (of r & z), and then substitute the numbers. but now with the procedure you suggested, Maple can find the answer immediately.

Maple is kidding me!!

sara_ph — Wed, 04 Jan 2012 10:36:24 Z

Dear Prof. Israel,

First it sounds right, but now..

Now I’ve examined the function and have found that with the procedure you suggested, Maple first put the numerical values of r and z into the complicated function f(r,z) and then compute the integral over the third parameter!!

What shall I do? There must be some numerical way of computing the integral of such complicated functions, but what??

Like this?

Robert Israel — Fri, 06 Jan 2012 01:32:41 Z

@sara_ph : Nobody is kidding anybody. I was (and am still) not sure what you wanted Maple to do. Do you mean something like this?
This will produce a numerical approximation of the integral for any values of the parameters.

> B:= unapply(Student[Calculus1][ApproximateInt](f(r,z,teta), teta=0 .. 0.78, method=simpson, partition=100), r, z):

Then:

> B(2,3);

You are right..

sara_ph — Sun, 08 Jan 2012 15:52:48 Z

@Robert Israel I do apolagize if I have bothered you, I didn't mean it.

yes, something like this will help. Function definition is also correct but it fails at zero points of r and z, because in the integrand there is (for example) r*cos(teta) , by subsituting r=0 this one will be eliminated from integration which sounds wrong.

I have now 3 other questions. I will be glad if you (or any other person) could help me...

1. Is it possible for Maple to compute an integral false?

2. How can we reduce the computation time for an integral?(Still I have not examined your latest command line) Does Maple run slower than Mathlab for a similar program?

3. while running my program an error report appeared: "kernel connection has been lost" and it stopped running, needed to be restarted. How can I avoid this error?

Many Thanks...