[spd,xd,yd] = GenerateCIEDay(Temp,[B])
Generate CIE daylights of the desired correlated color
temperature. Formulae are from W+S, pp. 145-146.
The required basis vectors may be obtained by loading
the file B_cieday.
Temp - row vector of color temperatures. These should be
in the range 4000 - 25000.
B - CIE daylight basis vectors.
spd - desired spectral power distributions
xd - row vector of x chromaticities
yd - row vector of y chromaticities
9/28/93 dhb, jms Changed argument name to Temp
If B not passed, return spd =  and other data