poisspdf (Statistics Toolbox)

Poisson probability density function (pdf)

Syntax

```
Y = poisspdf(X,LAMBDA)
```

Description

poisspdf(X,LAMBDA) computes the Poisson pdf at each of the values in X using the corresponding parameters in LAMBDA. Vector or matrix inputs for X and LAMBDA must be the same size. A scalar input is expanded to a constant matrix with the same dimensions as the other input. The parameters in LAMBDA must all be positive.

The Poisson pdf is

where x can be any nonnegative integer. The density function is zero unless x is an integer.

Examples

A computer hard disk manufacturer has observed that flaws occur randomly in the manufacturing process at the average rate of two flaws in a 4 Gb hard disk and has found this rate to be acceptable. What is the probability that a disk will be manufactured with no defects?

In this problem, = 2 and x = 0.

```
p = poisspdf(0,2)
p =
    0.1353
```

poissinv poissrnd