library(lattice)

size <- 10
X  <-  mat.or.vec((size+1)*(size+1),3)
tick <- mat.or.vec(size+1,1)
for (i in 0:size) {
  tick[i+1] <- i/(size+1.0)
  for (j in 0:size) {
    ij  <-  (size+1)*j+i+1
    X[ij,1]  <-  1.0
    X[ij,2]  <-  i/(size+1.0)
    X[ij,3]  <-  j/(size+1.0)
  }
}

b <- c(1.2573658, -1.4135946, -0.4723616)

pred <- X%*%b

g <- data.frame(x1=X[,2],x2=X[,3],y=pred)

train <- read.table("loans.dat",header=F,col.names=c("x1","x2","y"))

source("psopts.r")

trellis.device(postscript,onefile=F,print.it=F,color=T,file="regr01.eps")
print(wireframe(g$y~g$x1*g$x2,g))
dev.off()

trellis.device(postscript,onefile=F,print.it=F,color=T,file="regr02.eps")
print(cloud(train$y~train$x1*train$x2,train))
dev.off()