Power series - pointwise

From JSXGraph Wiki
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

Approximate the value of

[math]\displaystyle{ \sum_{n=0}^\infty a_n\cdot x^n }[/math]

for various values of [math]\displaystyle{ x }[/math]. Drag the point 'x', the blue point shows the value of the above series.

nth-coefficient: , start summation at n =

The underlying JavaScript code

var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-8,8,8,-8], axis:true, showClearTraces: true});

var p = board.create('glider', [0, 0, board.defaultAxes.x] , {name: 'x'});
var q = board.create('point', [0, 1], {name: '', color: 'blue', trace: true, fixed: true});

p.on('up', function(evt) {

  var x, n, s, m = 50;
  var txtraw = document.getElementById('input').value;
  var a_n = board.jc.snippet(txtraw, true, 'x, n', true);
  var n_0 = parseInt(document.getElementById('startval').value);

  x = p.X();
  for (n = n_0, s = 0; n < m; n++) {
    s += a_n(x, n);
  q.moveTo([x, s], 0);