dat<-data.frame(x=c(2,3,4,5,6),y=c(4,4,6,6,10))

N = length(dat$x)
x<-dat$x
y<-dat$y

min.RSS <- function(param1, param2, x, y, N) {
    beta0 = param1
    beta1 = param2
    RSS = vector("numeric",length(beta0))
    for (i in 1:length(beta0)){
        RSS[i] = sum((param1[i]+param2[i]*x-y)^2)
    }
    return(RSS)
}

param1 <- seq(0.1, 1.1, by=0.05)
names(param1) <- param1
param2 <- seq(1, 2, by=0.05)
names(param2) <- param2

z <- outer(X = param1, Y = param2, FUN = min.RSS, N = N, x = x, y = y)
min(z)
zd<-data.frame(z)

inds = which(zd == min(zd), arr.ind=TRUE)
inds
(rnames = rownames(zd)[inds[,1]])
(cnames = colnames(zd)[inds[,2]])

require(lattice)
wireframe(z, drape=T, xlab="beta0", ylab="beta1", zlab="RSS",col.regions=rainbow(100))
wireframe(z, xlab="beta0", ylab="beta1", zlab="RSS")

# test it out
min.RSS(param1[3], param2[3],  x = x, y = y, N = N)
z[3,3]