initialize


  <script>
  //compile("coffee");
  //source = document.getElementById("coffee").innerText;
  //JS = CoffeeScript.compile(source);
  //alert(JS);
  //eval(JS);
  //cube = window.cube;
  //alert(window.JS);
  function setfv() {
    f=document.getElementById('fv').value;
  }
  
    a = 2.5;
    xmode = 0;
    thestroke = "blue";
    compile("coffee");
    cube = window.cube;
    square = window.square; 
  
  function toggle() {
    if (xmode == 1) { thestroke = "blue"; xmode = 0; }
    else { thestroke = "red"; xmode = 1; }
    // alert("update");
    update();
    }
  function xstroke() { return thestroke; }
  
  function update () {
  f=document.getElementById('fv').value;
    p = []
    with (Math) 
      for (var x = -a; x < a+.1; x += .1)
        // p[p.length] = [x, x-x*x*x]
        //p[p.length] = [x, eval(f)]
        p[p.length] = [x, cube(x)]
    stroke = xstroke()
    //path(p,"func")
    //stroke = "blue"
    plot(f,-a,a)
    setText(f,"fval")
    setText(a.toFixed(2),"aval")
    setText((-a).toFixed(2),"maval")
  }
  </script>
  <h5>
  y=<span id="fval">f</span>
  <input type="text" id="fv" name="fname" value="cube(x)" onblur="toggle()" />
  for <span id="maval">a <=x<= a</span>
  <input type="button" value="-" onclick="a-=.25;update()"/>
  <input type="button" value="+" onclick="a+=.25;update()"/>
  </h5>
  </center>
  </body>