- class torch.nn.MSELoss(size_average=None, reduce=None, reduction='mean')¶
Creates a criterion that measures the mean squared error (squared L2 norm) between each element in the input and target .
The unreduced (i.e. with
'none') loss can be described as:
where is the batch size. If
and are tensors of arbitrary shapes with a total of elements each.
The mean operation still operates over all the elements, and divides by .
The division by can be avoided if one sets
reduction = 'sum'.
size_average (bool, optional) – Deprecated (see
reduction). By default, the losses are averaged over each loss element in the batch. Note that for some losses, there are multiple elements per sample. If the field
size_averageis set to
False, the losses are instead summed for each minibatch. Ignored when
reduce (bool, optional) – Deprecated (see
reduction). By default, the losses are averaged or summed over observations for each minibatch depending on
False, returns a loss per batch element instead and ignores
reduction (str, optional) – Specifies the reduction to apply to the output:
'none': no reduction will be applied,
'mean': the sum of the output will be divided by the number of elements in the output,
'sum': the output will be summed. Note:
reduceare in the process of being deprecated, and in the meantime, specifying either of those two args will override
Input: , where means any number of dimensions.
Target: , same shape as the input.
>>> loss = nn.MSELoss() >>> input = torch.randn(3, 5, requires_grad=True) >>> target = torch.randn(3, 5) >>> output = loss(input, target) >>> output.backward()