I want to graph R vs. g for n=0,1 and 2.

I want to graph R vs g for g=[0, 0.5]

Y axis is restricted (0 to 0.25)

[reem123]

@Star Strider

[Walter Roberson]

What error message did you get when you implemented this yourself?

[reem123]

to check when perturbation theory breaks.

[Walter Roberson]

@reem123

We are not going to write your code for you. You need to make a start on the programming. We will help you with the problems you encounter with your implementation.

[reem123]

Ok, Thank you.

But please I don't know how to put double factorial in my equation, which code for double factorial.

For example I want to write y=x!! ?

[Torsten]

(6*n-1)!! = (6*n)! /( 2^(3*n) * (3*n)! )

Section "Relation to the factorial" under

https://en.wikipedia.org/wiki/Double_factorial

[John D'Errico]

As a hint, I would compute each term as the sum of the logs of each part of those elements. Only at the end do you exponentiate the result. If not, expect to rapidly see underflows or overflows, or maybe both at once.

As a second hint, how do you compute the log of a factorial? The simplest way is to use the relationship of the factorial to the gamma function, and to then realize that MATLAB provides the function gammaln, which computes the natural log of the gamma function.

Alternatively, you would find that Stirling's approximation is actually quite accurate for the factorial, and it is easily logged. Or, you could compute the log of a factorial as the sum of the logs of the integers in the necessary product. Even so, just use gammaln.

Finally, Torsten gave you a relation for the double factorial

In the end though, you need to put it together as this is your assignment, not ours. At the very least, you need to make a credible effort.