mweibull <- function(mean, stdev)
# Returns the Method-of-Moments shape and scale parameter estimates
# for the Weibull distribution, given a mean and variance.
# Method:  Garcia, O.  NZ Journal of Forestry Science
# Use help("dweibull") for definitions and more details.
{
    cv <- stdev / mean
    if (cv > 1.2 || cv <= 0)
        stop("Out of range")
    a <- 1 / (cv * (((((0.007454537 * cv * cv - 0.08354348) * cv + 0.153109251) *
        cv - 0.001946641) * cv - 0.22000991) * (1 - cv) * (1 - cv) + 1))
    list(shape = a, scale = mean / gamma(1 + 1 / a))
}