[R] Solving equations involving gamma functions

[Berend Hasselman]

Shant Ch wrote:
> 
> Hi,
> 
> I want to find a value of n1. I used the following code but I am getting
> the 
> error - 
> 
> 
> Error in as.vector(x, mode) : 
>   cannot coerce type 'closure' to vector of type 'any'
> 
> 
> n=10
> a_g<-(1/(n*(n-1)))*((pi/3)*(n+1)+(2*sqrt(3)*(n-2))-4*n+6)
> 
> a_s<-function(n1)
> {
>   t1=(n1-1)/2;
>   (t1*(gamma(t1)/gamma(n1/2))^2)/2-1-a_g
> }
> xm<-solve(a_s)
>  

Have you looked in the documentation for solve?
Have you done  

?solve

You will see that solve is for solving systems of linear equations.

First you should graph your function to get some idea where the zero (if
there is one) is.
For example

curve(a_s,from=1.1,to=10)

and then start narrowing down the range

curve(a_s,from=1.3,to=2)

and finally use uniroot to find a zero:

?uniroot
uniroot(a_s,c(1.3,2))

I hope this wasn't homework.

/Berend
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