Chapter 2.3, Problem 79E

For each of these partial functions, determine its domain, codomain, domain of definition, and the set of values for which it is undefined. Also, determine whether it is a total function.

   $f:\text{Z}\to \text{R},f\left(n\right)=1/n$

   $f:\text{Z}\to Z,f\left(n\right)=\lceil n/2\rceil$

   $f:\text{Z}\times Z\to \text{Q},f\left(m,n\right)=m/n$

   $f:\text{Z}\times Z\to \text{Z},f\left(m,n\right)=mn$

   $f:\text{Z}\times Z\to \text{Z},f\left(m,n\right)=m-n\text{if }m>n$