chainer.functions.logsumexp

chainer.functions.logsumexp(x, axis=None)[source]

Log-sum-exp of array elements over a given axis.

This function calculates logarithm of sum of exponential of array elements.

\[y_i = \log\left(\sum_j \exp(x_{ij})\right)\]
Parameters
  • x (Variable or N-dimensional array) – Elements to log-sum-exp.

  • axis (None, int, or tuple of int) – Axis which a sum is performed. The default (axis = None) is perform a sum over all the dimensions of the input array.

Returns

Output variable.

Return type

Variable