code: public static double[] calcInverseSunVector( double[] sunVector ) {
          double m = Math.max(Math.abs(sunVector[0]), Math.abs(sunVector[1]));
          return new double[]{-sunVector[0] / m, -sunVector[1] / m, -sunVector[2] / m};
      }
docs: Calculating the inverse of the sun vector.
  
  @param sunVector
  @return