nbincdf (Statistics Toolbox)

Negative binomial cumulative distribution function.

Syntax

Y = nbincdf(X,R,P)

Description

Y = nbincdf(X,R,P) returns the negative binomial cumulative distributionfunction with parameters R and P at the values in X.

The size of Y is the common size of the input arguments. A scalar input functions as a constant matrix of the same size as the other inputs.

The negative binomial cdf is:

The motivation for the negative binomial is performing successive trials each having a constant probability, P, of success. What you want to find out is how many extra trials you must do to observe a given number, R, of successes.

Example

x = (0:15);
p = nbincdf(x,3,0.5);
stairs(x,p)