function Cos (x: Real): Real;
or
function Cos (z: Complex): Complex;
Cos returns the cosine of the argument. The result is in the range -1 < Cos (x) < 1 for real arguments.
The function Cos is defined in ISO 7185 Pascal; its application to complex values is defined in ISO 10206 Extended Pascal.
program CosDemo; begin { yields 0.5 since Cos (Pi / 3) = 0.5 } WriteLn (Cos (Pi / 3) : 0 : 5) end.