A function returning to the same value at regular intervals.
- ‘His results concern the approximation theory of almost periodic functions.’
- ‘In particular he had found a continuous periodic function whose trigonometric interpolating polynomials, corresponding to equally spaces mesh points, diverge almost everywhere.’
- ‘This is where any mathematical function is expressed as the sum of an infinite series of other periodic functions.’
- ‘This has been done by subtracting a periodic function from the data.’
- ‘These turned out to be doubly periodic functions and are called elliptic functions.’