func writedat(filename, x, y, x_precision=3, y_precision=5) {
    var fh = File(filename).open_w
 
    for a,b in (x ~Z y) {
        fh.printf("%.*g\t%.*g\n", x_precision, a, y_precision, b)
    }
 
    fh.close
}
 
var x = [1, 2, 3, 1e11]
var y = x.map{.sqrt}
 
writedat('sqrt.dat', x, y)