function V(n)
{
	var v = parseInt($(n).value);
	if(isNaN(v)) v = 0;
	$(n).value = v;
	return v;
}

function R(n)
{
	return Math.round(n * 100) / 100;
}

function inflate(current, interest, years)
{
	for (var i =0; i < years; i++)
	{
		current *= 1 + interest / 100;
	}
	return current;
}

function out(id, value)
{
  $(id).innerHTML = Math.round(value * 100) / 100;
}

function $() {
  var elements = new Array();

  for (var i = 0; i < arguments.length; i++) {
    var element = arguments[i];
    if (typeof element == 'string')
      element = document.getElementById(element);

    if (arguments.length == 1) 
      return element;

    elements.push(element);
  }

  return elements;
}

function newton(fct, guess)
{
	var eps = 0.001;
	var old_guess = guess * .98 + 0.1;
	var y;
	while(Math.abs(y = fct(guess)) > eps)
	{
		var dydx = (y - fct(old_guess)) / (guess - old_guess);
		old_guess = guess;
		guess = old_guess - y / dydx;
	}
	return guess;
}