Second derivative of the density Created by Stephen Jewson using Deriv() by Andrew Clausen and Serguei Sokol
gev_p12_fdd(x, t1, t2, v1, v2, v3, v4, v5)
Matrix
a vector of training data values
a vector of predictors for the mean
a vector of predictors for the sd
first parameter
second parameter
third parameter
fourth parameter
fifth parameter