Table lookup is a common solution when a FPU isn't available and speed is a higher priority than accuracy. I've actually used formulas for trig functions befor

Table lookup is a common solution when a FPU isn't available and speed is a higher priority than accuracy. I've actually used formulas for trig functions before with IEEE double floating-point until the accuracy didn't improve. (think it was a continued fraction or or some other technique I didn't understand, didn't -lm or something for builtin functions and worked around it lol...) It was very slow! Makes your computer's fan spin faster, even changes the smell in the room while grinding away!