**digraph_arc**,
a Fortran90 code which
carries out operations on digraphs, a directed graph.
Information is stored in an arc list, pairs of nodes forming edges.
Operations include computing in- and out-degrees,
computing the in- and out-degree sequences, counting the edges,
printing the arc list, generating fixed and random examples.

The computer code and data files described and made available on this web page are distributed under the MIT license

**digraph_arc** is available in
a Fortran90 version.

cities, a FORTRAN90 code which handles various problems associated with a set of "cities" on a map.

codepack, a FORTRAN90 code which computes "codes" that can determine if two graphs are isomorphic.

color_digraph_adj, a Fortran90 code which carries out operations on color digraphs, a directed graph in which each node has been assigned a color. That information is stored in an adjacency matrix in which the diagonal elements record colors. Operations include counting the colors, computing in- and out-degrees, computing the in- and out-degree sequences, counting the edges, printing the adjacency matrix, generating fixed and random examples.

color_graph_adj, a Fortran90 code which carries out operations on color graphs, an undirected graph in which each node has been assigned a color. That information is stored in an adjacency matrix in which the diagonal elements record colors. Operations include counting the colors, computing degrees, computing the degree sequences, counting the edges, printing the adjacency matrix, generating fixed and random examples.

digraph_adj, a Fortran90 code which carries out operations on digraphs, a directed graph. Information is stored in an adjacency matrix. Operations include computing in- and out-degrees, computing the in- and out-degree sequences, counting the edges, printing the adjacency matrix, generating fixed and random examples.

floyd, a FORTRAN90 code which implements Floyd's algorithm for finding the shortest distance between pairs of nodes on a directed graph.

graph_representation, a data directory which contains examples of ways of representing abstract mathematical graphs

graph_theory, a Fortran90 code which carries out operations on abstract graphs, such as a breadth-first-search, the computation of a minimum spanning tree, an Euler or Hamilton circuit, blocks, chromatic polynomial, or transitive closure. Objects include undirected and directed graphs, weighted graphs, and trees.

grf, a data directory which contains a description of the GRF format and some examples.

grf_io, a FORTRAN90 code which reads and writes GRF files.

maze, a Fortran90 code which carries out operations on a maze, including the diameter, a random example, or a path that solves the maze.

toms097, a FORTRAN90 code which computes the distance between all pairs of nodes in a directed graph with weighted edges, using Floyd's algorithm.

treepack, a FORTRAN90 code which carries out computations on trees, a simple kind of graph that is minimally connected.

- digraph_arc.f90, the source code;
- digraph_arc.sh, compiles the source code;