Find mean of Weibull 3 distribution in R

Question

Given alpha, lambda and phi (shape, scale and "guarantee"time (time before any failures), how do I find the mean of the distribution?
qweibull3 gives the median.
rweibull3 makes a nice random sample that approximates the mean, but is not the theoretical value.

Answer 1

Looking for definitions from wiki: https://en.wikipedia.org/wiki/Weibull_distribution

weibull3_mean <- function(gtime, shape, scale) {
    gtime + scale*gamma(1.0+1.0/shape)
}