As explained in the JAX FAQ, jax.numpy.where has suprising behavior when its gradient is taken and one of the inputs is NaN.  This CL adds a short description of the behavior to the jax.numpy.where docs, which is the logical place that users would look for it.
As explained in the JAX FAQ, jax.numpy.where has suprising behavior when
its gradient is taken and one of the inputs is NaN.  This CL adds
a short description of the behavior to the jax.numpy.where docs,
which is the logical place that users would look for it.

PiperOrigin-RevId: 488654036

google/jax,google/jax,google/jax,google/jax