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Random Generation of bi-directional Graphs in Omnet, Omar Usman
Published in Khyber.ORG on Wednesday, July 4 2012 (http://www.khyber.org)

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لمنځ ، محمد عمر خېوه وال

حضرت عمر فاروق (رض) نه درسول الله (ص) دا ارشاد مبارک نقل شوے دے چې داسلام بنياد په پنځو ستنو باندې دے دټولونه اول په کلمى طيبې سره ددې ګواهى وکړى چې دالله نه سيوا هيڅوک دعبادت لائق نشته اومحمد (ص) دالله رسول دے دې نه پس مونځ قائمول زکات ادا کول حج کول او درمضان المبارک روژې نيول . . . . نور

په اسلام اباد کښې د لال جومات او حفصې مدرسې لانجې نن سبا په ورځپاڼو او نورو ډله ايزو رسنيو کښې په سر کښې ځاے موندې دے. او هره ګړۍ نوی نوی خبرونه مخې ته راځی. خو دا يواځې د لال جومات يا يوې مدرسې خبره نه ده بلکې دا . . . نور

The excerpts below are from a two hour interview of Ghani Khan at Lady Reading Hospital in Peshawar, NWFP. Ghani Khan had recently been shown on Pakistani television for the first time. He was about to be discharged after a minor ailment. . . . Read More

Shilmani , F S Shilmani

Shalmani's predominantly live in Shalman Valley in Khyber Agency near Peshawar where they share their land with the Afridi's, Shinwari's and Malagori's. Their sub-tribes are the Alim Zai, Tarak Zai, and Kam Shalman. These people have strong relationships with Mohmand's. . . . Read More

کاکاجى صنوبر حسين دبرصغير دازادۍ د وړومبى صف دمبارزو نه ؤ هغه نۀ يوازې په ژبه او قلم دازادۍ په جنګ کښې حصه اخستې وه بلکې ددې دپاره ئې په عملى توګه هم جدوجهد کړے ؤ او دغه وجه وه چې دانګريزانو دسترګو ازغے ؤ نو ځکه هغه هم لکه دترنګزو دحاجى صيب ډير ژوند په ازاده قبائلى علاقه کښې تير کړے ؤ . . . نور

افغانستان مو خپل کور دې ، ذبيح الله شريفی

. . . نور

Random Generation of bi-directional Graphs in Omnet

Omar Usman

Publishing Date: Wednesday, July 4 2012

The Omnet usman.html manual has code for generation of random topologies. The type of network generated can contain uni-directional, or bi-directional edges. Usually, people working with networks require generation of bi-directional graphs only. What you will see here is a small hack to the Omnet Engine, which can enable you to do that. (Note: I am not an expert on Omnet so most probably there is another simpler way of doing this. If you do, please leave a comment).

The files you need to modify are:

  1. src/sim/distrib.cc
  2. include/distrib.h
  3. src/sim/nedfunctions.cc

Modifications to distrib.cc

You need to create a new function (runiform). What this does is that it retains the random number generated from a previous call to uniform(). The random number is generated every 2-calls.

double runiform(int rng) {
static int r = 0;
static double l = 0;
if(r%2 == 0) l = uniform(0,1);
return l;

Modifications to distrib.h

Just one line to be modified here:

SIM_API double runiform(int rng=0);

Modifications to nedfunctions.cc

The current usman.html manual (July 4, 2012) shows a different way of doing this. The code in the manual is not consistent with what I found in the source (4.2.2). You need to add the following code to where the other continuous random variate generation code is present.

"quantity runiform(int rng?)",
"Retains the value generated from a previous call to uniform()",
int rng = argc==2 ? (int)argv[1] : 0;
return cNEDValue(runiform(rng), argv[0].getUnit());

Compilation and Usage

If you have already compiled omnet once, you can simply run make and compile the engine again. When complete, fire up your editor and open your .NED file. You can now generate bi-directional graphs using the following code from the manual (which is adopted to this hack):

module RandomGraph {
int count;
double connectedness; // 0.0 submodules:
node[count]: Node {
connections allowunconnected:
for i=0..count-1, for j=0..count-1 {
node[i].out[j] --> node[j].in[i]
if i<j && runiform() > connectedness;
node[j].out[i] --> node[i].in[j]
if i<j && runiform() > connectedness;

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Random Generation of bi-directional Graphs in Omnet, Omar Usman
Published in Khyber.ORG on Wednesday, July 4 2012 (http://www.khyber.org)