Definition:Domain of Mapping/Also known as

Definition
The domain of (usually) a mapping is sometimes called the departure set.

Some sources refer to $\Dom f$ as the domain of definition of $f$.

Others refer to it on occasion as the source, but this is not recommended as there are other uses for that term.

, for example, possibly forgetting themselves, in Appendix $\text{A}.7$:


 * Here are some common functions and their inverses. Note how carefully the source and codomain are specified.

Some sources denote the domain of $f$ by $\map {\mathrm D} f$.

Some sources use $D_f$.