You only need to mix two different wavelengths to render any human perceptible color. They give you four parameters to work with (wavelength1, brightness1, wave

You only need to mix two different wavelengths to render any human perceptible color. They give you four parameters to work with (wavelength1, brightness1, wavelength2, brightness2) which makes it an underdetermined system with an infinite number of solutions for all but the pure, spectral boundary of the gamut.