Since when is it necessary for a color to be generated by a single wavelength of electromagnetic radiation? A good way to look at colors their perceptual relati

Since when is it necessary for a color to be generated by a single wavelength of electromagnetic radiation? A good way to look at colors their perceptual relationships such as complimentary color is the color wheel used in the HSL and HSV color models. Magenta is at 324° by the way; that's between red and blue (more towards red). Going to the opposite side of the color wheel (324°-180°=144°) gives you (surprise) green, the complementary color to magenta. Magenta happens to be the area where the color wheel "joins" the opposite ends of the visible electromagnetic spectrum. There is nothing mystical about that fact which explains why greens is the only color that has a complementary color that is not made from a single wavelength.