source('../../Data/data_loaders.R')

DF = load_particle_board_data()

# Form the centered temperature variable:
#
DF$TEMPC = DF$temperature - mean(DF$temperature)
DF$TEMPC2 = DF$TEMPC^2

# Show that these two columns are orthogonal:
#
sum( DF$TEMPC * DF$TEMPC2 )