Optimization of an integrated function in R

Question

I would like to find the optimum value of a for the following integration which is a function of x

  integrand <- function(x,a) {
          D=a/((x+1)*sqrt(x+a))
          D
        }

I can do the integration for fixed value of a . For example, if a=5

> integrate(integrand,0,5,a=5)$value
[1] 3.490687

But I want to find the optimum value using the optim() function in R or any available built-in optimization function. I have tried the following code, unfortunately it is not working,

optim(5,integrate(integrand, lower = 0, upper = 5))

Any help is appreciated.

Answer 1

You can use the 'optimize' function, which is ideal for one-parameter optimization:

optimize(f = integrand, interval = c(0, 5), a = 5)