tf.gradients(ys, xs, grad_ys=None, name='gradients', colocate_gradients_with_ops=False, gate_gradients=False, aggregation_method=None)

tf.gradients(ys, xs, grad_ys=None, name='gradients', colocate_gradients_with_ops=False, gate_gradients=False, aggregation_method=None)

See the guide: Training > Gradient Computation

Constructs symbolic partial derivatives of sum of ys w.r.t. x in xs.

ys and xs are each a Tensor or a list of tensors. grad_ys is a list of Tensor, holding the gradients received by the ys. The list must be the same length as ys.

gradients() adds ops to the graph to output the partial derivatives of ys with respect to xs. It returns a list of Tensor of length len(xs) where each tensor is the sum(dy/dx) for y in ys.

grad_ys is a list of tensors of the same length as ys that holds the initial gradients for each y in ys. When grad_ys is None, we fill in a tensor of '1's of the shape of y for each y in ys. A user can provide their own initial grad_ys to compute the derivatives using a different initial gradient for each y (e.g., if one wanted to weight the gradient differently for each value in each y).

Args:

  • ys: A Tensor or list of tensors to be differentiated.
  • xs: A Tensor or list of tensors to be used for differentiation.
  • grad_ys: Optional. A Tensor or list of tensors the same size as ys and holding the gradients computed for each y in ys.
  • name: Optional name to use for grouping all the gradient ops together. defaults to 'gradients'.
  • colocate_gradients_with_ops: If True, try colocating gradients with the corresponding op.
  • gate_gradients: If True, add a tuple around the gradients returned for an operations. This avoids some race conditions.
  • aggregation_method: Specifies the method used to combine gradient terms. Accepted values are constants defined in the class AggregationMethod.

Returns:

A list of sum(dy/dx) for each x in xs.

Raises:

  • LookupError: if one of the operations between x and y does not have a registered gradient function.
  • ValueError: if the arguments are invalid.

Defined in tensorflow/python/ops/gradients_impl.py.