code: function(signal1, signal2, options){
      options = options || {};
      options = _.defaults(options, defaultOptions);
      
      // ensure signal2 is not longer than signal2
      if(signal1.length < signal2.length){
        var tmp = signal1;
        signal1 = signal2;
        signal2 = tmp;
      }
      
      if(options.method == "cauchy"){
        return cauchy(signal1,signal2,options);
      } else {
        return specConvolution(signal1, signal2,options);
      }
    }
docs: the convolution function assumes two discrete signals
  that have the same spacing