cyl = SensorToCyl
Convert from sensor to cylindrical coordinates.
This is designed for use with the CIE Lxx color
spaces, so it's assumed that the first input
coordinate is luminance and this is taken directly
as height. The next two input coordiantes are
assumed to be chromaticity coords.
The returned cylindrical system is luminance, radius, angle,
with radius and angle computed in the passed chromaticity plane.
Note that angle is returned in radians.
We use the conventions of the CIE Lxx color spaces
See also CylToSensor
10/17/93 dhb Wrote it by converting CAP C code.
2/20/94 jms Added single argument case to avoid cData.
4/5/02 dhb, ly New calling interface.
11/06/06 dhb No longer allow two passed args.
1/3/10 dhb Elaborated comments a little.