# How do we use igrah for large graph

I have used igraph for implement an algorithm to solve community detection problem large graph (with 300k nodes eq amazon social network) , the complexity of the algorithm is O(n²) and i get result for small graph but for large graph the code dose not work despite it run on HPC ? is igraph scale well ?

It is not quite clear what you are asking. Can you please be a bit more specific?

Are you saying that you are running an igraph function which is claimed by the documentation to have a complexity of O(n^2) (for what meaning of n? vertices? edges?), but empirically you observe a worse complexity than this? If so, can you demonstrate the problem with a small example? If this is not what you meant, please clarify the question.

I mean the complexity of the algorithm O(n^2) where n is the number of verticies …the implementation( the code ) with igraph package witch I use the igraph function …the code run well in small graph and midium graph like (as-j22jullia06 with n = 22000 nodes )but il large graph with 300k node like amazon ) the code dose not work well

Which algorithm are you using? What time did it take on 22000 nodes? How long did you wait to process 300k nodes?