Create sine lookup table in C++

Question

How can I rewrite the following pseudocode in C++?

real array sine_table[-1000..1000]
    for x from -1000 to 1000
        sine_table[x] := sine(pi * x / 100         


        

Answer 1

One more point: calling trigonometric functions is pricey. if you want to prepare the lookup table for sine with constant step - you may save the calculation time, in expense of some potential precision loss.

Consider your minimal step is "a". That is, you need sin(a), sin(2a), sin(3a), ...

Then you may do the following trick: First calculate sin(a) and cos(a). Then for every consecutive step use the following trigonometric equalities:

• sin([n+1] * a) = sin(n*a) * cos(a) + cos(n*a) * sin(a)
• cos([n+1] * a) = cos(n*a) * cos(a) - sin(n*a) * sin(a)

The drawback of this method is that during this procedure the round-off error is accumulated.