U
    d#	                     @   s`   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	 d dl
mZ G dd deZdS )	    N)inf)constraints)AbsTransform)Cauchy)TransformedDistributionc                       s   e Zd ZdZdejiZejZdZ	d fdd	Z
d fdd	Zed	d
 Zedd Zedd Zedd Zdd Zdd Zdd Zdd Z  ZS )
HalfCauchyaz  
    Creates a half-Cauchy distribution parameterized by `scale` where::

        X ~ Cauchy(0, scale)
        Y = |X| ~ HalfCauchy(scale)

    Example::

        >>> m = HalfCauchy(torch.tensor([1.0]))
        >>> m.sample()  # half-cauchy distributed with scale=1
        tensor([ 2.3214])

    Args:
        scale (float or Tensor): scale of the full Cauchy distribution
    scaleTNc                    s*   t d|dd}tt| j|t |d d S )Nr   F)validate_args)r   superr   __init__r   )selfr   r	   	base_dist	__class__ C/tmp/pip-unpacked-wheel-ua33x9lu/torch/distributions/half_cauchy.pyr      s    zHalfCauchy.__init__c                    s    |  t|}tt| j||dS )N)	_instance)Z_get_checked_instancer   r
   expand)r   Zbatch_shaper   newr   r   r   r   $   s    zHalfCauchy.expandc                 C   s   | j jS N)r   r   r   r   r   r   r   (   s    zHalfCauchy.scalec                 C   s    t j|  tj| jj| jjdS )Ndtypedevice)torchfullZ_extended_shapemathr   r   r   r   r   r   r   r   mean,   s    zHalfCauchy.meanc                 C   s   t | jS r   )r   Z
zeros_liker   r   r   r   r   mode0   s    zHalfCauchy.modec                 C   s   | j jS r   )r   variancer   r   r   r   r   4   s    zHalfCauchy.variancec                 C   s\   | j r| | tj|| jjj| jjjd}| j|t	
d }t |||jdk < |S )Nr      r   )_validate_args_validate_sampler   Z	as_tensorr   r   r   r   log_probr   logr   r   shape)r   valuer#   r   r   r   r#   8   s    
zHalfCauchy.log_probc                 C   s$   | j r| | d| j| d S )Nr       )r!   r"   r   cdf)r   r&   r   r   r   r(   A   s    
zHalfCauchy.cdfc                 C   s   | j |d d S )Nr'   r    )r   icdf)r   Zprobr   r   r   r)   F   s    zHalfCauchy.icdfc                 C   s   | j  td S )Nr    )r   entropyr   r$   r   r   r   r   r*   I   s    zHalfCauchy.entropy)N)N)__name__
__module____qualname____doc__r   ZpositiveZarg_constraintsZnonnegativeZsupportZhas_rsampler   r   propertyr   r   r   r   r#   r(   r)   r*   __classcell__r   r   r   r   r      s$   




	r   )r   r   Z
torch._sixr   Ztorch.distributionsr   Ztorch.distributions.transformsr   Ztorch.distributions.cauchyr   Z,torch.distributions.transformed_distributionr   r   r   r   r   r   <module>   s   