Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

Implementing simple binary probability distribution.

Posted on 2000-04-24
4
315 Views
Last Modified: 2010-04-15
Using C/C++, I would like the computer to randomly fill some array with either 0s or 1s, in some proportion p.  That is, let Array be some n dimensional array.  Then, for every i, I want Array[i] = 0 with probability p and = 1 with probability 1-p.
0
Comment
Question by:mm162
  • 2
4 Comments
 
LVL 1

Accepted Solution

by:
snifong earned 50 total points
ID: 2745074
int p = 40; // probability for 0
int q = 1 - p; // 1 - probability for 1
srand() = time(NULL);
for loop here with counter i...
if (rand() % 100 <= p)
   Array[i] = 0;
else
   Array[i] = 1;
end for loop
0
 
LVL 22

Expert Comment

by:cookre
ID: 2745089
Assuming you have the function 'rand()' that returns an int x, 0<=x<=RAND_MAX, and given probability float p, 0<=p<=1, then:

1) For a given p, compute
int CutPoint;
CutPoint=(int) (.5+p*(float)RANDMAX);

2) For any i, compute
if   (rand()>=CutPoint) Array[i]=1;
else                    Array[i]=0;




0
 
LVL 84

Expert Comment

by:ozo
ID: 2745090
int p = 40; // probability for 0
Probabilities are never greater than 1

int q = 1 - p; // 1 - probability for 1
Nor can probabilities be negative
0
 
LVL 22

Expert Comment

by:cookre
ID: 2745312
'struth ozo, but how many folks browse locked questions?  I know I don't.  I suppose I ought to start...
0

Featured Post

How Do You Stack Up Against Your Peers?

With today’s modern enterprise so dependent on digital infrastructures, the impact of major incidents has increased dramatically. Grab the report now to gain insight into how your organization ranks against your peers and learn best-in-class strategies to resolve incidents.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Want to delete all my personal data 13 146
Using ANSI C how to Read a .csv file 10 94
Windows Updates failing due to Diskpart not configured correctly 8 129
Super Scope, DHCP 5 91
Have you thought about creating an iPhone application (app), but didn't even know where to get started? Here's how: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Important pre-programming comments: I’ve never tri…
An Outlet in Cocoa is a persistent reference to a GUI control; it connects a property (a variable) to a control.  For example, it is common to create an Outlet for the text field GUI control and change the text that appears in this field via that Ou…
The goal of this video is to provide viewers with basic examples to understand and use structures in the C programming language.
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use nested-loops in the C programming language.

808 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question