FAQ

make terminates with fatal error: igraph.h: No such file or directory

Be sure that igraph header files are placed in a standard system include directory. If these headers are in non-standard places, you have to tell the gcc where to find them. Open the Makefile and assign to IGRAPH_INCDIR_1 (or, equivalently, to IGRAPH_INCDIR_2) the path to the folder containing igraph header files on your system.

make terminates with ld: cannot find -ligraph

This is the linker which cannot find the igraph shared library. Make sure that this library is installed in a directory in the default library path. The directory should be listed in the file /etc/ld.so.conf. The igraph installation procedure should place it in a standard place so you might want to try reinstalling it.

Why does the utility maximal_cliques take too long to terminate?

As discussed in [MaximalCliquesListing], the executable maximal_cliques uses the igraph C library to extract maximal cliques. Versions of igraph less than 0.6 (e.g. 0.5.4) do not implement the fast Bron-Kerbosh algorithm. Therefore you should be sure to have at least version 0.6 installed.