question: public static void formatDouble ( double source , int decimals , int precision , StringBuffer target ) { int scale = ( Math . abs ( source ) >= 1.0 ) ? decimals : precision ; if ( tooManyDigitsUsed ( source , scale ) || tooCloseToRound ( source , scale ) ) { formatDoublePrecise ( source , decimals , precision , target ) ; } else { formatDoubleFast ( source , decimals , precision , target ) ; } }
target:  Rounds the given source value at the given precision and writes the rounded value into the given target