[ns] How to write on a tracefile and run Xgraph

[Abhinav Singhal]

Dear friends,
I have developed a new routing algorithm based on genetics.As the result of
my code,I have the values of two variables set:No. of elements and No. of
generations.
I need to plot a graph between these two variables.For that, I need to write
them to a tracefile.
How do I do that?
Please reply with a proper code.
Thanx in advance.