code: function(signal1, signal2, options){
      options = options || {};
      options.epsilon = options.epsilon || 1E-08;
      var sig1 = Signal(signal1);
      var sig2 = Signal(signal2);
      if(signal1.length != signal2.length) return false;
      var diffSQ = _.reduce(_.range(signal1.length), function(d,idx){
        var diff = (sig1[idx].value-sig2[idx].value);
          return d + diff * diff;
      },0);
      return diffSQ/signal1.length < options.epsilon;
    }
docs: determines if two signals can be considered equal.