# PoissonV

Generates Poisson distributed random values with varying mean.

## Syntax

Fortran:

status = virngpoissonv( method, stream, n, r, lambda )

C:

status = viRngPoissonV( method, stream, n, r, lambda );

## Description

This function generates n Poisson distributed random numbers xi(i = 1, ..., n) with distribution parameter `λi`, where `λi∈R`; `λi > 0`.

The probability distribution is given by:

The cumulative distribution function is as follows:

## Input Parameters

Name | Type | Description
--- | --- | ---
method | FORTRAN: INTEGER, INTENT(IN) C: int | Generation method. The specific value is as follows: `VSL_METHOD_IPOISSONV_POISNORM` See brief description of the POISNORM method in Table“Values of `<method>` in method parameter”
stream | FORTRAN: TYPE (VSL_STREAM_STATE), INTENT(IN) C: VSLStreamStatePtr | FORTRAN: Descriptor of the stream state structure. C: Pointer to the stream state structure
n | FORTRAN: INTEGER, INTENT(IN) C: int | Number of random values to be generated
lambda | FORTRAN: DOUBLE PRECISION, INTENT(IN) C: double* | Array of n distribution parameters `λi`.

## Output Parameters

Name | Type | Description
--- | --- | ---
r | FORTRAN: INTEGER, INTENT(OUT) C: int* | Vector of n Poisson distributed random values

## Return Values

VSL_ERROR_OK, VSL_STATUS_OK
  Indicates no error, execution is successful.
VSL_ERROR_NULL_PTR
  stream is a NULL pointer.
VSL_ERROR_BAD_STREAM

  stream is not a valid random stream.

VSL_ERROR_BAD_UPDATE

  Callback function for an abstract BRNG returns an invalid number of updated entries in a buffer, that is, `< 0` or `> nmax`.

VSL_ERROR_NO_NUMBERS

  Callback function for an abstract BRNG returns 0 as the number of updated entries in a buffer.

Parent topic: Discrete Distributions