What are some quality graph libraries for C?

I'm writing some C where I'm going to need to store a very large graph as an adjacency matrix. I was going to hack up a quick graph implementation, but wanted to ask first if there开发者_运维知识库 are any good graph libraries for C (not c++) that people like.

I'm going to import the graph in some standard format (probably GML, but thats not a make or break requirement), store it as an adjacency matrix, and then do some computations.

Any thoughts?

Thanks!

EDIT: as an FYI, I have no interest in drawing the graph at all

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You can have a look at igraph. It also has support for reading and writing GML files.