question: private void calculateDelta ( double [ ] b ) { double numerator = 0.0 ; double denominator = 0.0 ; double sign = 1.0 ; for ( int k = 0 ; k < b . length ; k ++ ) { if ( k < mExtremalIndices . size ( ) ) { int extremalIndex = mExtremalIndices . get ( k ) ; numerator += ( b [ k ] * mGrid . getDesiredResponse ( ) [ extremalIndex ] ) ; denominator += b [ k ] * sign / mGrid . getWeight ( ) [ extremalIndex ] ; sign = - sign ; } else { mLog . error ( "Something went wrong -- the length of b exceeds the set of extremal indices" ) ; } } mDelta = numerator / denominator ; }
target:  Calculates the value of delta that represents the maximum ripple for the current set of  extremal indices (L+2) Implements Oppenheim/Schafer Discrete Time Signal Processing, 3e, 2016, equation 114