DistGamma

class pydsol.core.distributions.DistGamma(stream: StreamInterface, shape: float, scale: float)

Bases: DistContinuous

The Gamma distribution is a continuous distribution that yields positive numbers. The gamma distribution represents the time to complete some task, e.g. customer service or machine repair. The parameters are not rate-related, but average-related, so the mean is (shape * scale) and the variance is (shape * scale ** 2).

__init__(stream: StreamInterface, shape: float, scale: float)

Constructs a new Gamma distribution, with two parameters: shape and scale. The Gamma distribution is a continuous distribution and will return a positive number. The Gamma distribution represents the time to complete some task, e.g. customer service or machine repair. The parameters are not rate-related, but average-related, so the mean is (shape * scale) and the variance is (shape * scale ** 2).

Parameters:

• stream (StreamInterface) – the random stream to use for this distribution

• shape (float or int) – the shape parameter, also called alpha or k

• scale (float or int) – the scale parameter, also called beta or theta

Raises:

• TypeError – when stream is not implementing StreamInterface:

• TypeError – when shape or scale is not a float or int:

• ValueError – when shape <= 0 or scale <= 0:

draw() → float

Draw a value from the Gamma distribution. Based on the algorithm in Law & Kelton, Simulation Modeling and Analysis, 1991, pages 488-489.

probability_density(x: float) → float

Returns the probability density value for value x.

property shape: float

Return the parameter value shape, also called alpha or k

property scale: float

Return the parameter value scale, also called beta or theta

property stream: StreamInterface

Return the current random stream for this distribution.