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## [igraph] Re: betweenness and degree correlation

 From: Tamas Nepusz Subject: [igraph] Re: betweenness and degree correlation Date: Tue, 23 Jun 2009 22:22:55 +0100

```Hi Yong,

```
Are you sure you are using the patched igraph version (the one that uses a long double to count the number of shortest paths)? If so, can you check how many bytes does a long double use on your platform? (It's 16 bytes on mine, both on OS X and on openSuSE). You can use the following program:
```
#include <stdio.h>
int main(int argc, char* argv[]) {
printf("%d\n", sizeof(long double));
return 0;
}

--
Tamas

On 2009.06.23., at 18:55, Yong Zou wrote:

```
```Hi Tamas,

Here is my result: 1189955308309381376.000000, vertex 433

```
I did in the following way (exactly the same way as we discussed last time):
```igraph_read_graph_edgelist(&graph, f_edge, 0, IGRAPH_UNDIRECTED);
```
igraph_betweenness(&graph, &result, igraph_vss_all(), IGRAPH_UNDIRECTED);
```
What's wrong here?

Thanks,
Yong

On Tue, Jun 23, 2009 at 6:03 PM, Tamas Nepusz<address@hidden> wrote:
```
```Hi Yong,

```
```For the betweenness centrality, it seems very easy to have overflow
now for my other network. Please have a look at my attachment (edge
```
list), which has only 1000 nodes. But I really want to analyze the BC
```for this network.
```
```The betweenness calculation seems fine for me for this network; i.e.,
the maximum betweenness is 3641.928 and the minimum is zero. What are

```
Another problem is about the degree-degree correlation, namely, I want
```to calculate something P(k'|k) which is so called assortativity
coefficient. But I'm sorry I couldn't find it somewhere from igraph.
```
This is not implemented directly in igraph, but it's fairly simple (at least if you are thinking about the assortativity coefficient as defined
```by Newman). This is calculated in Python as follows:

http://snipplr.com/view/9914/calculating-assortativity-coefficient-in-igraph/

I guess it's not too complicated to translate this back to C.

--
Tamas

```
```

```