R中的Excel求解器

Question

I have been trying to find something similar to excel solver in r .

For example I have the following program:

L=2.4
UCL=L; LCL=-L
ARL=1/(pnorm(LCL, mean = 0, sd = 1, lower.tail = TRUE)+pnorm(UCL, mean = 0, 
sd = 1, lower.tail = FALSE))

I want r to search for a value of "L" such that my resultant "ARL" is close to eg 200.

Is there a way to do so in r?

Answer 1

f <- function(L) {
  UCL=L; LCL=-L
  ARL=1/(pnorm(LCL, mean = 0, sd = 1, lower.tail = TRUE)+pnorm(UCL, mean = 0, 
                                                               sd = 1, lower.tail = FALSE))
  ARL-200
}

uniroot(f,c(1,10))

It will return

$root
[1] 2.807

$f.root
[1] -0.0003725

$iter
[1] 13

$init.it
[1] NA

$estim.prec
[1] 6.532e-05

So the solution is L=2.807 and it took 13 iterations.