# degree(Digraph,Thing) -- returns the degree of a vertex in a digraph

## Synopsis

• Function: degree
• Usage:
x = degree(D,v)
• Inputs:
• D, an instance of the type Digraph,
• v, , a vertex in the graph/digraph
• Outputs:

## Description

In a simple graph, the degree of a vertex is the number of neighbors of the vertex. In a digraph, we define the degree of a vertex to be the number of elements in the unique union of the parents and children of the vertex.

 i1 : D = digraph({1,2,3,4},{{1,2},{2,3},{3,4},{4,2},{2,4}}); i2 : degree(D, 3) o2 = 2 i3 : degree(D, 2) o3 = 3