This global floating-point constant approximates one-quarter of Pi.
See Also:
IlcArcCos, IlcArcSin, IlcArcTan, IlcCos, IlcDegToRad, IlcHalfPi, IlcPi, IlcRadToDeg, IlcSin, IlcTan, IlcThreeHalfPi, IlcTwoPi