eval_over_grid_with_batch: Evaluate function over grid of points
In CollinErickson/contour: Create Contour Plots from Data or a Function

'batchmax' gives how many can be evaluated at a time. If more than 1, then the input is given to the function as rows of a matrix.

1	eval_over_grid_with_batch(x, y, fn, batchmax)

`x`	Vector of x values to evaluate
`y`	Vector of y values to evaluate
`fn`	Function that takes in a length two vector if 'batchmax' is 1 or a matrix with two columns if greater than 1.
`batchmax`	Number of points that can evaluated simultaneously. If 1, points are passed to 'fn' as a vector of length two. If greater than 1, points are passed to 'fn' as rows of a matrix.

Matrix of size 'length(x)' by 'length(y)'

1 2	eval_over_grid_with_batch(c(0,.5,1), c(10,20,30), function(a)a[1]+a[2], batchmax=1) eval_over_grid_with_batch(c(0,.5,1), c(10,20,30), function(a)a[,1]+a[,2], batchmax=Inf)