R : Copyright 2003, The R Development Core Team
Version 1.6.2  (2003-01-10)

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> invisible(options(echo = TRUE))
> train <- read.table("loans.dat",header=F,col.names=c("x1","x2","y"));
> 
> x1 <- train$x1;
> x2 <- train$x2;
> 
> one <- mat.or.vec(length(x1),1) + 1.0;
> X <- cbind(one,x1,x2,x1*x2,x1^2,x2^2);
> y  <- train$y;
> 
> fit <- lsfit(X,y,intercept=FALSE);
> b <- as.numeric(fit$coef);
> 
> y  <- train$y;
> y <- (y==1);
> 
> size <- 100;
> grid <- mat.or.vec((size+1)*(size+1),2);
> for (i in 0:size) {
+ for (j in 0:size) {
+   grid[(size+1)*j+i+1,1] <- i;
+   grid[(size+1)*j+i+1,2] <- j;
+ }
+ }
> grid <- grid/(size+1);
> 
> gx1 <- grid[,1];
> gx2 <- grid[,2];
> 
> one <- mat.or.vec(length(gx1),1) + 1.0;  
> X <- cbind(one,gx1,gx2,gx1*gx2,gx1^2,gx2^2); 
> 
> pred <- X%*%b;
> dflt <- (pred > 0.5);
> 
> edge <- ((0.489<pred)&(pred<0.513));
> 
> source("psopts.r");
> postscript(file="quad.eps");
> 
> plot(x=x1,y=x2,type='n',xlab="FICO Score",ylab="P-Index");
> points(x=x1[y],y=x2[y],pch='o',col="red");
> points(x=x1[!y],y=x2[!y],pch='o',col="green");
> points(grid[dflt,],pch='.',col="red");
> points(grid[!dflt,],pch='.',col="green");
> points(grid[edge,],pch="+",cex=0.4);
> 
> dev.off();
null device 
          1 
> 
> test <- read.table("eval.dat",header=F,col.names=c("x1","x2","y"));
> 
> tx1 <- test$x1;
> tx2 <- test$x2;
> ty  <- test$y;
> 
> one <- mat.or.vec(length(tx1),1) + 1.0;  
> X <- cbind(one,tx1,tx2,tx1*tx2,tx1^2,tx2^2);
> 
> pred <- X%*%b; 
> dflt <- (pred > 0.5);
> 
> dflt <- as.numeric(dflt);
> 
> err <- abs(dflt-ty);
> print(mean(err));
[1] 0.07807
> proc.time()
[1] 2.68 0.11 2.78 0.00 0.00
>