Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 11/07/2023
Public

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Document Table of Contents

vRngGamma

Generates gamma distributed random values.

Syntax

status = vsrnggamma( method, stream, n, r, alpha, a, beta )

status = vdrnggamma( method, stream, n, r, alpha, a, beta )

Include Files

  • mkl.fi, mkl_vsl.f90

Input Parameters

Name

Type

Description

method

INTEGER, INTENT(IN)

Generation method. The specific values are as follows:

VSL_RNG_METHOD_GAMMA_GNORM
VSL_RNG_METHOD_GAMMA_GNORM_ACCURATE

Acceptance/rejection method using random numbers with Gaussian distribution. See brief description of the method GNORM in Table "Values of <method> in method parameter"

stream

TYPE (VSL_STREAM_STATE), INTENT(IN)

Descriptor of the stream state structure

n

INTEGER, INTENT(IN)

Number of random values to be generated

alpha

DOUBLE PRECISION for vdrnggamma

REAL(KIND=4), INTENT(IN) for vsrnggamma

REAL(KIND=8), INTENT(IN) for vdrnggamma

Shape α.

a

DOUBLE PRECISION for vdrnggamma

REAL(KIND=4), INTENT(IN) for vsrnggamma

REAL(KIND=8), INTENT(IN) for vdrnggamma

Displacement a.

beta

DOUBLE PRECISION for vdrnggamma

REAL(KIND=4), INTENT(IN) for vsrnggamma

REAL(KIND=8), INTENT(IN) for vdrnggamma

Scalefactor β.

Output Parameters

Name

Type

Description

r

DOUBLE PRECISION for vdrnggamma

REAL(KIND=4), INTENT(OUT) for vsrnggamma

REAL(KIND=8), INTENT(OUT) for vdrnggamma

Vector of n random numbers with gamma distribution

Description

The vRngGamma function generates random numbers with gamma distribution that has shape parameter α, displacement a, and scale parameter β, where α, β, and a∈R ; α > 0, β > 0.

The probability density function is given by:


Equation

where Γ(α) is the complete gamma function.

The cumulative distribution function is as follows:


Equation

Product and Performance Information

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.

Notice revision #20201201

Return Values

VSL_ERROR_OK, VSL_STATUS_OK

Indicates no error, execution is successful.

VSL_ERROR_NULL_PTR

stream is a NULL pointer.

VSL_RNG_ERROR_BAD_STREAM

stream is not a valid random stream.

VSL_RNG_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_RNG_ERROR_NO_NUMBERS

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

VSL_RNG_ERROR_QRNG_PERIOD_ELAPSED

Period of the generator has been exceeded.

VSL_RNG_ERROR_NONDETERM_NRETRIES_EXCEEDED

Number of retries to generate a random number by using non-deterministic random number generator exceeds threshold.

VSL_RNG_ERROR_ARS5_NOT_SUPPORTED

ARS-5 random number generator is not supported on the CPU running the application.