# Spectral luminous efficiency as a function of wavelength

I've come across plenty of figures demonstrating the spectral luminous efficiency as a function of wavelength (meaning the humans eye's sensitivity to different wavelengths) http://www.yorku.ca/eye/photopik.htm but I've been unable to find the equation which gives this function so I can plot it myself.

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The reason you don't often see a function for it is that it's an empirical measurement, not a prediction from theory. Any function you find will simply be some sort of fit to the data. It may be useful for calculations, but it's really nothing more than an interpolation of the data. –  Colin K Jan 30 '13 at 16:13