Dear R experts,
I am trying to find all the solutions of an equation. Here is an example:


integrand1<- function(x){1/x*dnorm(x)}
integrand2<- function(x){1/(2*x-50)*dnorm(x)}

integrand3<- function(x,C){
  cd<- 1/(x+C)
  return(cd)
}

res<- function(C){
  ce<-integrate(integrand1, lower=1, upper=50)$value+ integrate(integrand2,
lower=50, upper=100)$value-integrate(integrand3, C=C,lower=1,
upper=100)$value
  return(ce)
}

I want to find all the roots of res.

First, I used uniroot to ensure that a solution existed, and it works.
uniroot(res, c(1,1000))

But,  there might be other roots, and I wanted to use the function uniroot.
library(rootSolve)
uniroot.all(res, c(1,1000))

I obtain an error message:
"Error in integrate(integrand3, C = C, lower = 1, upper = 100) :
  evaluation of function gave a result of wrong length
In addition: Warning message:
In x + C : longer object length is not a multiple of shorter object length"

I don't understand what is wrong? Thank you very much for any suggestion!
Aurelien

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