function IsZero(const A: Extended; Epsilon: Extended): Boolean; function IsZero(const A: Double; Epsilon: Double): Boolean; function IsZero(const A: Single; Epsilon: Single): Boolean; This function determines whether value A is within Epsilon of zero. If Epsilon is omitted or zero, then the following tolerance is used (as of Delphi 2005): Extended: 1e-16 Double: 1e-12 Single: 1e-4