Throughout the Wolfram Language there is support not only for approximate real numbers, but also for exact numbers represented in algebraic or symbolic form. Functions like Floor, IntegerPart, and Max are all in effect set up to "prove theorems"—often using original algorithms developed at Wolfram Research—to give values with exact inputs.
Abs — absolute value
Sign — sign (, , )
Clip — clip to between and or other limits
Rescale — rescale to run between and
Chop — chop small values to
Threshold — set values in a list below a threshold to 0.
LogisticSigmoid — sigmoid function
Unitize — 0 for x0, and 1 otherwise
UnitStep — 0 for , and 1 for
Piecewise — general piecewise function
DiscreteIndicator — indicator function for a discrete set
IntegerQ — test whether an expression is an integer