FLOYD
Shortest Distances Between Nodes in a Directed Graph

FLOYD is a FORTRAN77 library which demonstrates Floyd's algorithm for finding the shortest distance between every pair of nodes in a directed graph.

Licensing:

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

Languages:

FLOYD is available in a C version and a C++ version and a FORTRAN90 version and a FORTRAN77 version and a MATLAB version.

Related Data and Programs:

BELLMAN_FORD, a FORTRAN77 library which implements the Bellman-Ford algorithm for finding the shortest distance from a given node to all other nodes in a directed graph whose edges have been assigned real-valued lengths.

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

CITIES, a dataset directory which contains a number of city distance datasets.

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

DIJKSTRA, a FORTRAN77 program which runs a simple example of Dijkstra's minimum distance algorithm for graphs.

GRAFPACK, a FORTRAN90 library which computes various quantities associated with mathematical graphs.

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

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

GRF_IO, a FORTRAN90 library which reads and writes GRF files.

GRF_TO_EPS, a FORTRAN90 library which can make an encapsulated PostScript image of a GRF file.

TOMS097, a FORTRAN77 library which computes the distance between all pairs of nodes in a directed graph with weighted edges, using Floyd's algorithm.

Reference:

1. Robert Floyd,
   Algorithm 97: Shortest Path,
   Communications of the ACM,
   Volume 5, Number 6, page 345, June 1962.
2. Michael Quinn,
   Parallel Programming in C with MPI and OpenMP,
   McGraw-Hill, 2004,
   ISBN13: 978-0071232654,
   LC: QA76.73.C15.Q55.

Source Code:

• floyd.f, the source code.
• floyd.sh, commands to compile the source code.

Examples and Tests:

• floyd_prb.f, a sample calling program.
• floyd_prb.sh, commands to compile and run the sample program.
• floyd_prb_output.txt, the output file.

List of Routines:

• I4_HUGE returns a "huge" I4.
• I4MAT_FLOYD finds the shortest I4 distances between pairs of nodes in a directed graph.
• I4MAT_PRINT prints an I4MAT.
• I4MAT_PRINT_SOME prints some of an I4MAT.
• R8_HUGE returns a very large R8.
• R8MAT_FLOYD finds the shortest R8 distances between pairs of nodes in a directed graph.
• R8MAT_PRINT prints an R8MAT.
• R8MAT_PRINT_SOME prints some of an R8MAT.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the FORTRAN90 source codes.