Period of cosh

Theorem

The following formula holds for all $k \in \mathbb{Z}$: $$\cosh(z+2\pi i k)=\cosh(z),$$ where $\cosh$ denotes the hyperbolic cosine, $\pi$ denotes pi, and $i$ denotes the imaginary number.

References

• 1964: Milton Abramowitz and Irene A. Stegun: Handbook of mathematical functions ... (previous) ... (next): $4.5.14$