BELLMAN_FORD, a FORTRAN90 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.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
BELLMAN_FORD is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version and a Python version.
DIJKSTRA, a FORTRAN90 library which implements a simple version of Dijkstra's minimum distance algorithm for graphs.
FLOYD, a FORTRAN90 library which implements Floyd's algorithm for finding the shortest distance between pairs of nodes on a directed graph.
TOMS097, a FORTRAN90 library which computes the distance between all pairs of nodes in a directed graph with weighted edges, using Floyd's algorithm.
You can go up one level to the FORTRAN90 source codes.