U
    d
                     @   st   d dl mZ d dlZd dlZd dlmZ d dlmZ d dlm	Z	 d dl
mZmZ d dlmZmZ G dd	 d	e	ZdS )
    )NumberN)constraints)Uniform)TransformedDistribution)AffineTransformExpTransform)broadcast_alleuler_constantc                       s   e Zd ZdZejejdZejZd fdd	Z	d fdd	Z
dd	 Zed
d Zedd Zedd Zedd Zdd Z  ZS )Gumbela}  
    Samples from a Gumbel Distribution.

    Examples::

        >>> m = Gumbel(torch.tensor([1.0]), torch.tensor([2.0]))
        >>> m.sample()  # sample from Gumbel distribution with loc=1, scale=2
        tensor([ 1.0124])

    Args:
        loc (float or Tensor): Location parameter of the distribution
        scale (float or Tensor): Scale parameter of the distribution
    locscaleNc                    s   t ||\| _| _t| jj}t|trHt|trHt|j	d|j
 }n&tt| j|j	t| jd|j
 }t jtdt| j dt jt|| j dg}tt| j|||d d S )N   r   r   )validate_args)r   r   r   torchfinfoZdtype
isinstancer   r   ZtinyZepsZ	full_liker   invr   Z	ones_likesuperr
   __init__)selfr   r   r   r   Z	base_distZ
transforms	__class__ >/tmp/pip-unpacked-wheel-ua33x9lu/torch/distributions/gumbel.pyr      s     zGumbel.__init__c                    s<   |  t|}| j||_| j||_tt| j||dS )N)	_instance)Z_get_checked_instancer
   r   expandr   r   )r   Zbatch_shaper   newr   r   r   r   (   s    zGumbel.expandc                 C   s6   | j r| | | j| | j }||  | j  S N)Z_validate_argsZ_validate_sampler   r   explog)r   valueyr   r   r   log_prob/   s    
zGumbel.log_probc                 C   s   | j | jt  S r   )r   r   r	   r   r   r   r   mean5   s    zGumbel.meanc                 C   s   | j S r   )r   r$   r   r   r   mode9   s    zGumbel.modec                 C   s   t jt d | j S )N   )mathpisqrtr   r$   r   r   r   stddev=   s    zGumbel.stddevc                 C   s   | j dS )N   )r+   powr$   r   r   r   varianceA   s    zGumbel.variancec                 C   s   | j  dt  S )Nr   )r   r    r	   r$   r   r   r   entropyE   s    zGumbel.entropy)N)N)__name__
__module____qualname____doc__r   realZpositiveZarg_constraintsZsupportr   r   r#   propertyr%   r&   r+   r.   r/   __classcell__r   r   r   r   r
      s   



r
   )Znumbersr   r(   r   Ztorch.distributionsr   Ztorch.distributions.uniformr   Z,torch.distributions.transformed_distributionr   Ztorch.distributions.transformsr   r   Ztorch.distributions.utilsr   r	   r
   r   r   r   r   <module>   s   