Math: codomain vs range
Tutoring math, definitions are important. The tutor mentions a couple.
The codomain of a function is the set of its possible outputs, while its range is the set that actually is output.
Let’s imagine you plan to measure the mass of each athlete on a team (possibly because it’s a weight-class sport, such as wrestling). First, the domain is the set of athletes on the team. Next, the codomain, CD, is all possible values of their masses, m: you might suggest, if it’s a high school team, it’s possibly CD={mass m such that m>=35kg and m<=130kg}.
The range, R, is the set of masses you indeed do measure from them. If there are five athletes, it might turn out to be R={40.2, 70.5, 65.2, 100.1,80.2}. The range is a subset of the codomain.
Source:
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.