Assume that we have where is an interval and should lie in an arbitrary range. The procedure Filtre_Arc_Cos allows to update the range for . It returns -1 is and are incompatible, 0 otherwise. Its syntax is:
int Filtre_Arc_Cos(INTERVAL &U,INTERVAL &beta)A similar procedure exist for the inverse sine with
The procedure Arc_Cos_Multiple allows to determine all possible ranges for , assuming that is restricted to a range included in ::
int Arc_Cos_Multiple(INTERVAL &U,INTERVAL &beta,INTERVAL_VECTOR &BETA)This procedure returns the number of possible ranges for and their values in BETA.