code: public static double[] xVals(double[] vector) {
  
  
          if (vector == null)
              return null;
          double[] x = new double[vector.length / 2];
          int count = 0;
          for (int i = 0; i < vector.length; i++) {
              if (i % 2 != 0)
                  x[count++] = vector[i];
          }
          return x;
      }
docs: This returns the x values of the given vector.
  These are assumed to be the even values of the vector.
  @param vector the vector to getFromOrigin the values for
  @return the x values of the given vector