torch.digamma¶

torch.digamma(input, *, out=None) → Tensor¶

Computes the logarithmic derivative of the gamma function on input.

\psi(x) = \frac{d}{dx} \ln\left(\Gamma\left(x\right)\right) = \frac{\Gamma'(x)}{\Gamma(x)}

Parameters: input (Tensor) – the tensor to compute the digamma function on
Keyword Arguments: out (Tensor, optional) – the output tensor.

Note

This function is similar to SciPy’s scipy.special.digamma.

Note

From PyTorch 1.8 onwards, the digamma function returns -Inf for 0. Previously it returned NaN for 0.

Example:

>>> a = torch.tensor([1, 0.5])
>>> torch.digamma(a)
tensor([-0.5772, -1.9635])

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