How to Calculate Chromaticity Coordinates of LEDs from Dominant Wavelength

[pramodp]

I tried searching for this topic in various forums, but haven't yet found a straight forward answer. For LEDs, there are two ways of expressing their colour - by specifying the dominant wavelength, and by providing the x-y chromaticity coordinates of the output. My question is, how do we convert the former into the latter? There are a handful of sites and tools that do it for you, such as **broken link removed**, but I want to figure out how to do that myself.

Any help will get brownie points