[R] Use of outer

[Rafael Jimenez]

Dear list,

I have been trying to use the function outer to make contour plots of a
cost function for regression analysis with no success. (see commented
code below).

Could anybody give me some advice on what I am doing wrong, or what is
relevant for me to read?

Thanks,
Rafael

## ============================================= CODE
## Create vectors and matrix
Y <- c(0.5116403,2.4055245,1.6596707,1.8286057,2.6119199)

col.1 <- c(0.8997692,0.8216292,0.6449104,0.8179743,0.6602276)
col.2 <- c(0.01175669,0.89389797,0.19913807,0.29872301,0.66144258)

X <- cbind(col.1, col.2)

## Define function
## Give default values so that it "takes two arguments"
J <- function (x1, x2, X.val=X, Y.val=Y) {
    t(Y.val-X.val[,1]*x1-X.val[,2]*x2) %*% (Y.val-X.val[,1]*x1-X.val[,2]*x2)
}

## Get grid to plot
theta.1 <- array(seq(-1, 1, length=10))
theta.2 <- theta.1

## How to do this with outer?
z.matrix <- outer(theta.1, theta.2, "J")

## Plot
contour(theta.1, theta.2, z.matrix)