question: public DoubleArrayList quantileElements ( DoubleArrayList phis ) { if ( precomputeEpsilon <= 0.0 ) return super . quantileElements ( phis ) ; int quantilesToPrecompute = ( int ) Utils . epsilonCeiling ( 1.0 / precomputeEpsilon ) ; phis = phis . copy ( ) ; double e = precomputeEpsilon ; for ( int index = phis . size ( ) ; -- index >= 0 ; ) { double phi = phis . get ( index ) ; int i = ( int ) Math . round ( ( ( 2.0 * phi / e ) - 1.0 ) / 2.0 ) ; i = Math . min ( quantilesToPrecompute - 1 , Math . max ( 0 , i ) ) ; double augmentedPhi = ( e / 2.0 ) * ( 1 + 2 * i ) ; phis . set ( index , augmentedPhi ) ; } return super . quantileElements ( phis ) ; }
target:  Computes the specified quantile elements over the values previously added.