[R] upper bound in the integrate function depends on a parameter

David Winsemius dwinsemius at comcast.net
Sun Dec 4 06:06:17 CET 2011

On Dec 3, 2011, at 10:23 PM, grttt nbbfg wrote:

> Sorry for my English, is not my first language..
> I have some trouble in terms of using integrate function in R.
> fx is a function of m and x where m is supposed to be a unknown  
> parameter.

R is not an algebraic solver (and R-help is not a homework list.).

>> fx=function(m,x){
> + x*2/(3*m)*(1-x/(3*m))
> + }
> The problem is in upper bound, it depends on parameter m.
>> integrate(fx,lower=0,upper=3*m)$value
> Is it possible to use the integrate function when bounds depend on a
> parameter?

If it is known, yes. You could also do some investigation:

curve(x*2/(3*5)*(1-x/(3*5)), 0, 15)

> How to define m to solve this integral? The result should be m.

As I said, no homework answers here.

David Winsemius, MD
West Hartford, CT

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