(Random-Number Function)Rung-Shiang ChengDepartment of Computer and Communication, Kun Shan Universityrscheng@mail.ksu.edu.tw

Outline

? ANSI C

10RAND_MAX(1/2)Example

10RAND_MAX (2/2)

("0")

1. 2. n

1016Example: .

1016

0 ~ 1Example

0 ~ 1

m nExample: m + (rand() % (n m + 1) )

m n

mn

mn

m nm + (rand() / RAND_MAX) (n m)

m nCase 1: random (20, 60)

m nCase 2: random (0, 1)

NS-2NS-2?Network Simulator, version 2C++, OTCLRouter, Link, End point, TCP/IP protocolsEthernet, WiFi, Sensor Networks

(seed) (distribution) E.g. ParetoConstantUniformExponentialHyperExponentail

*

Uniform Distribution : min_: max_

*

NS-22(0 )

FTP

Error Model (Uniform Distribution)(1/2)TCL Scriptnode0node1( SimpleLink object)error rate : Specify error rateunit : Specify the unit of error (time, pkt, bits)Default: packetranvar : Specify the random variable for generating errors

Error Model (Uniform Distribution)(1/2)goodput

Error rate (1/2)AWK(sent_drop.awk)

Error rate (1/2)&: 5

? (Report)http://teachers.ksu.edu.tw/rscheng/illus/report.htm