rm(list=ls())
install.packages(“plot3D”)
library(plot3D)

#-----------------------------------------------------#
#---   Classical and Bayesian inference (AMS132)   ---#
#---   Class 7: maximum likelihood estimator      ---#
#-----------------------------------------------------#

#-- Loss function:
thetasec=seq(-10,10,len=100)
asec=seq(-10, 10, len=100)

# square error loss:
L=function(theta, a){(theta-a)^2}
Lpoints=outer(thetasec, asec, L)

persp3D(thetasec, asec, Lpoints, xlab=expression(theta), ylab=expression(a))
contour(thetasec, asec, Lpoints, xlab=expression(theta), ylab=expression(a))

# absolute error loss:
L=function(theta, a){abs(theta-a)}
Lpoints=outer(thetasec, asec, L)

persp3D(thetasec, asec, Lpoints, xlab=expression(theta), ylab=expression(a))
contour(thetasec, asec, Lpoints, xlab=expression(theta), ylab=expression(a))