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.’
‘These turned out to be doubly periodic functions and are called elliptic functions.’
‘This has been done by subtracting a periodic function from the data.’
‘This is where any mathematical function is expressed as the sum of an infinite series of other periodic functions.’
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