Wiktionary
n. (context analysis English) Any complex function measurable function whose range is finite.
Wikipedia
In the mathematical field of real analysis, a simple function is a real-valued function over a subset of the real line, similar to a step function. Simple functions are sufficiently 'nice' that using them makes mathematical reasoning, theory, and proof easier. For example simple functions attain only a finite number of values. Some authors also require simple functions to be measurable; as used in practice, they invariably are.
A basic example of a simple function is the floor function over the half-open interval [1,9), whose only values are {1,2,3,4,5,6,7,8}. A more advanced example is the Dirichlet function over the real line, which takes the value 1 if x is rational and 0 otherwise. (Thus the "simple" of "simple function" has a technical meaning somewhat at odds with common language.) Note also that all step functions are simple.
Simple functions are used as a first stage in the development of theories of integration, such as the Lebesgue integral, because it is easy to define integration for a simple function, and also, it is straightforward to approximate more general functions by sequences of simple functions.
Usage examples of "simple function".
All this, remember, comes from the simple function we defined, iterated over and over to produce pairs of (y,z) values corresponding to a particular choice of a and b.
It was a simple function, unremarkable, and easy for him now to ignore.
This was not the fault of the absent host-mind, but a simple function of fatigue.
It has one simple function, and that is to tap into our plane's computer, download our coordinates, and transmit them.
How many ways could one entitle the simple function of hearing problems and meeting people?