code: private double[][] concatenateArrays(double[][] first, double[][] second){
          // I am sure as hell that should be a better way to do this...
          double[][] result = new double[first.length][first[0].length + second[0].length];
          for(int i = 0; i < first.length; i++){
              for (int j = 0; j < (first[i].length + second[i].length); j++){
                  if( j < first[i].length){
                      result[i][j] = first[i][j];
                  } else{
                      result[i][j] = second[i][j - first[i].length];
                  }
              }
          }
          return result;
      }
docs: Concatenate two two dimensional arrays.
  Both arrays must have the same dimensions.
  
  @param first
  @param second
  @return