protected void compute() {

    if (inputFunction != null) function.set(inputFunction);

    function.setInterval(getDouble(from), getDouble(to));

    // Application.debug(function.getFunction().evaluate(new double[] {1,1}));

  }
  /**
   * Construct a function
   *
   * @param cons
   * @param label
   * @param f (x,y) function
   * @param from "from" values for each var
   * @param to "to" values for each var
   */
  public AlgoFunctionNVarND(
      Construction cons, String label, GeoFunctionNVar f, NumberValue[] from, NumberValue[] to) {

    this(cons, from, to);

    inputFunction = f;
    // function = new GeoFunctionNVar(cons, inputFunction.getFunction());//(GeoFunctionNVar)
    // inputFunction.copy();
    function = (GeoFunctionNVar) inputFunction.copy();

    // end of construction
    setInputOutput((NumberValue[]) null, (GeoNumeric[]) null);

    compute();
    function.setLabel(label);
  }
  /**
   * Construct a function
   *
   * @param cons
   * @param label
   * @param coords description of the function
   * @param localVar var of the function
   * @param from "from" values for each var
   * @param to "to" values for each var
   */
  public AlgoFunctionNVarND(
      Construction cons,
      String label,
      NumberValue[] coords,
      GeoNumeric[] localVar,
      NumberValue[] from,
      NumberValue[] to) {

    this(cons, from, to);

    // we need to create Function objects for the coord NumberValues,
    // so let's get the expressions of xcoord and ycoord and replace
    // the localVar by a functionVar
    FunctionVariable[] funVar = new FunctionVariable[localVar.length];
    for (int i = 0; i < localVar.length; i++) {
      funVar[i] = new FunctionVariable(kernel);
      funVar[i].setVarString(localVar[i].getLabel());
    }

    ExpressionNode[] exp = new ExpressionNode[coords.length];
    FunctionNVar[] fun = new FunctionNVar[coords.length];

    for (int i = 0; i < coords.length; i++) {
      exp[i] = kernel.convertNumberValueToExpressionNode(coords[i]);
      for (int j = 0; j < localVar.length; j++) exp[i].replace(localVar[j], funVar[j]);
      fun[i] = new FunctionNVar(exp[i], funVar);
    }

    // create the function
    function = new GeoFunctionNVar(cons, fun[0]);

    // end of construction
    setInputOutput(coords, localVar);

    compute();
    function.setLabel(label);
  }