Densities from MLE and cp
dinvgammasub(x, y, fd1 = 0.01, fd2 = 0.01, aderivs = TRUE)
A vector of parameter estimates, two pdf vectors, two cdf vectors
a vector of training data values
a vector of values at which to calculate the density and distribution functions
the fractional delta used in the numerical derivatives with respect to the parameter
the fractional delta used in the numerical derivatives with respect to the parameter
logical for whether to use analytic derivatives (instead of numerical)