[R] uniroot problem

[Troels Ring]

Dear friends and helpers - in the script below, uniroot is called with a
function CHB that calls a function, Charge. On its own, CHB apparently does
what is expected, but from within uniroot, problems appear. An error is
thrown 

Error in f(lower, ...) : could not find function "f"

So CHB is not seen or understood from within uniroot?

 

I'm on windows 10, 64 bit R version 3.5.1 (2018-07-02)

All best wishes

Troels

 

 

kw <- 1e-14

TOT <- 1

Pk1 <- 10^-2.16

Pk2 <- 10^-7.21

Pk3 <- 10^-12.32 

 

K <- c(Pk1,Pk2,Pk3)

f <- c(1,1,1)

H <- 10^-7.4

 

Charge <- function(TOT,f,K,H) 

{

  num <- c() 

  num[1] <- K[1]/(f[1]^2*H)

  for (i in 2:length(K)) num[i] <- i*prod(K[1:i])/(f[1]^i*f[i]*H^i)

  num <- sum(num) 

  denum <- c()

  denum[1] <- 1+ K[1]/(f[1]^2*H)

  for (i in 2:length(K)) denum[i] <- prod(K[1:i])/(f[1]^i*f[i]*H^i)

  denum <- sum(denum)

  num/denum

}

 

Na <- 0.140

Cl <- 0.1

 

CHB  <- function(Na,Cl,H,K,f,TOT) {Na-Cl+H-kw/(f[1]^2*H)-Charge(TOT,f,K,H)}

 

H <- uniroot(CHB,interval=c(1e-19,5),tol=.Machine$double.eps,maxiter=100000,

             Na=Na,Cl=Cl,K=K,TOT=TOT,f=f)$root

#Error in f(lower, ...) : could not find function "f"

 

 

CHB(Na,Cl,10^-7.4,K,f,TOT) # -1.567668 OK right!


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