## About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

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Poisson distribution expected value.

The expected value for a Poisson random variable is

where `λ`

is the mean parameter.

`npm install @stdlib/stats-base-dists-poisson-mean`

`var mean = require( '@stdlib/stats-base-dists-poisson-mean' );`

Returns the expected value of a Poisson distribution with mean parameter `lambda`

.

```
var v = mean( 9.0 );
// returns 9.0
v = mean( 0.5 );
// returns 0.5
```

If provided `lambda < 0`

, the function returns `NaN`

.

```
var v = mean( -1.0 );
// returns NaN
```

```
var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var mean = require( '@stdlib/stats-base-dists-poisson-mean' );
var lambda;
var v;
var i;
for ( i = 0; i < 10; i++ ) {
lambda = randu() * 20.0;
v = mean( lambda );
console.log( 'λ: %d, E(X;λ): %d', lambda.toFixed( 4 ), v.toFixed( 4 ) );
}
```

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

See LICENSE.

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