How to calculate a integration of a self-definite function in R?

Asked Nov 04 '14 at 02:13

Active Nov 04 '14 at 02:51

Viewed 81 times

I intend to calculate the variance of a method however the expression is quite a mess.

In order to calculate this, I used the most inefficient way. I defined a function "a" which is

a<-function(x){
  (x/2*exp(-x^2/4)/(1/(sqrt(2*pi)*sqrt(2))*exp(-(x-4)^2/(2*2)))-0.01831564)^2*(1/(sqrt(2*pi)*sqrt(2))*exp(-(x-4)^2/(2*2)))
}

and use the command

 integrate(a,lower=0,upper=Inf)

however it cannot show the result.what's wrong with my usage and is there any easy way to do this?Thanks!

the error message is

integrate(a, lower = 0, upper = Inf) : non-finite function value

edited Nov 04 '14 at 02:51

thor

asked Nov 04 '14 at 02:13

Si Yuancheng

the error message is----integrate(a, lower = 0, upper = Inf) : non-finite function value – Si Yuancheng Nov 04 '14 at 02:14
`a` appears to underflow: `curve(a,from=0,to=100,log="y")` – Ben Bolker Nov 04 '14 at 02:19
So actually it cannot count by R?thx – Si Yuancheng Nov 04 '14 at 09:20

0 Answers0