v_xs = [-1.0, -0.8, -0.6, -0.4, -0.2, 0.0, 0.2, 0.4, 0.6, 0.8, 1.0];
var chebyshev_ys = [ 0.1,  0.2,  0.3,  0.4,  0.5, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1];
var chebyshev_n = 11;
var chebyshev_i = 0;

function init_chebyshev(){
    for(var i = 0; i < chebyshev_n; ++i){
        chebyshev_xs[i] = chebyshev_node(i+1, chebyshev_n);
        chebyshev_ys[i] = Math.sqrt(1 - Math.pow(chebyshev_xs[i], 2))
    }
    chebyshev = document.getElementById("chebyshev");
    var canvas_rect = chebyshev.getBoundingClientRect();
  