Versine

The versine function $\mathrm{versin} \colon \mathbb{C} \rightarrow \mathbb{C}$ is defined by the formula $$\mathrm{versin}(z)=1-\cos(z),$$ where $ \cos$ denotes the cosine function.

References

• 1964: Milton Abramowitz and Irene A. Stegun: Handbook of mathematical functions ... (previous) ... (next): 4.3.147