[R] optimize()

dnz.marcio dnz.marcio at gmail.com
Thu Dec 8 20:27:13 CET 2011


Hi!

I have a difficulty in the use of function optimize(). Could you help me?
I want to maximize this function:

##### Logaritmo da distribuição condicional de alpha[i]

lp_alphai <- function(alphai, i, beta, tau, N){

t1 <- (N[i+1] - N[i])*log(alphai)
t2 <- - (N[i+1] - N[i])*alphai*log(beta[i]) 
t3 <- (alphai - 1)*sum(log(times[(N[i] + 1):N[i+1]])) 
t4 <- - exp(alphai*(log(tau[i+1]) - log(beta[i])))

t5 <- 0
if(i > 1)
t5 <- exp(alphai*(log(tau[i]) - log(beta[i])))

v <- t1 + t2 + t3 + t4 + t5

return(v)

                                                         }

Then, I've done:

optimize(lp_alphai, lower = 0, upper = 10, maximum = TRUE, tol =
0.00000000001, i = 1, beta = 125, tau = c(0,1900), N = c(0,236))$maximum

However, I face this problem:
Error in i + 1 : 'i' missing

I've been in this problem all this day, but, I can't find a solution.
Thank you.

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