A <function> $f:\mathbb R\to\mathbb R$ is <periodic> with period $\alpha>0$ when
$$
\boxed{f(x+\alpha)=f(x)\quad\text{for every }x\in\mathbb R.}
$$
The period need not be the smallest positive one; for example, every positive <integer> multiple of a period is also a period.

Solution

Past exam of the year 1 of the computer science course of the University of Oxford / 2015 / Discrete mathematics, continuous mathematics, and probability (resit) / 6 / a / i / Solution

 Solution (source code)