Re: [igraph] Question on igraph_integer_t and igraph_real_t

[Gábor Csárdi]

igraph was started a long time ago, even if not much from the original
code has remained. At that time I was concerned with some system
having sizeof(long int)==2. That's the historical reason for defining
igraph_integer_t as a double.

It is a decision that I regret now, but it would be quite hard to get
rid of it, it requires a lot of testing and retesting. In particular,
the vertex/edge ids in the graph should be long int, igraph would be
somewhat faster as well.

But for this change we need a good testing system first, and then,
maybe together with the painful change from 0-based indexing to
1-based in the R package, we can have it.

Gabor

On Mon, Jan 26, 2009 at 11:22 PM, Chris Wj <address@hidden> wrote:
> I was reading the code to understand the underlying mechanisms in igraph.
> This is probably more of a C programming question, but why is
> igraph_integer_t defined as a double?
>
>> typedef double igraph_integer_t;
>> typedef double igraph_real_t;
>
> At first, I thought this was to have 64-bits for storing graph and edge ids
> because the graphs can get quite large. What is the benefit over using a
> long int?
>
> -Chris
>
>
> _______________________________________________
> igraph-help mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/igraph-help
>
>



-- 
Gabor Csardi <address@hidden>     UNIL DGM