Definition:

Points on one

Points on the other

An arrow in the diagram has its tail on a point representing a selected number, $a$, on the source (domain) line.

The head of the arrow points to the function value, $f(a)$, for the number $a$, represented by a point on the target (co-domain) line.

Both lines are oriented with the larger numbers higher on the axes.

Both lines are oriented with the larger numbers further to the right.

In this resource, mapping diagrams will be displayed vertically.