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Topic: Random Number Generators
Replies: 1   Last Post: Dec 31, 1997 8:34 AM

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Posts: 2
Registered: 12/7/04
Random Number Generators
Posted: Dec 31, 1997 7:36 AM
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Deal all,

I have a query regarding the nature of rand() and randn() functions on
Matlab, a software I'm just starting out with.
How are the random number generators implemented? rand() on many computer
languages is a linear congruence generator with (of course) a finite
period. The period is dependent on an intelligent choice of constants (a,
b, c in the case shown below)

Typically, the linear congruence generator is

rand_no = ( a * prev_rand_no + b ) mod c
prev_rand_no = rand_no;

Obviously, c is the greatest random number possible.
To generate numbers between 0 and 1, the random number must then be
divided by (Rand_Max +1). For a good random generator, c = Rand_Max.

randn() may be implemented by transforming the uniform deviates generated
by rand() to normal random variables. The Box - Muller method is a
popular method.
How does Matlab go about generating its random numbers? What is the
period of rand()? I have to perform a simulation where the random number
generator is invoked lots of times, so these questions are critical to the
validity of my results.
Thank You for your help.


Manish Kaul 43 University Road,
Electrical Engineering IV Singapore 297875.
National University of Singapore. Tel: 65 - 352 4574

Drink wet cement and get really stoned.

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