Add the MulNoNan op.

tf2jax/_src/ops.py

@@ -1390,6 +1390,46 @@ def _func(x: jnp.ndarray, axis: jnp.ndarray) -> jnp.ndarray:
   return _func
 
 
+def _mul_no_nan_forward(x: jnp.ndarray, y: jnp.ndarray) -> jnp.ndarray:
+  """Returns zero if y is zero, even if x if infinite or NaN."""
+  mul = anp.multiply(x, y)
+  return jnp.where(y == 0.0, jnp.zeros_like(mul), mul)
+
+
+@register_operation("MulNoNan")
+def _mul_no_nan(proto):
+  """Parse a MulNoNan op."""
+  _check_attrs(proto, {"T"})
+
+  @jax.custom_gradient
+  def _func(
+      x: jnp.ndarray, y: jnp.ndarray
+  ) -> Tuple[
+      jnp.ndarray,
+      Callable[[jnp.ndarray], Tuple[jnp.ndarray, jnp.ndarray]],
+  ]:
+    def _grad(g: jnp.ndarray) -> Tuple[jnp.ndarray, jnp.ndarray]:
+      """Given upstream grad G and a Div op: Z = X*Y, the gradients are.
+
+        dX = G * Y
+        dY = X * G
+
+      Args:
+        g: Upstream gradient.
+
+      Returns:
+        forward value: mul_no_nan(x, y)
+        grad: Gradient information in TF format.
+      """
+      dx = _mul_no_nan_forward(g, y)
+      dy = _mul_no_nan_forward(x, g)
+      return dx, dy
+
+    return _mul_no_nan_forward(x, y), _grad
+
+  return _func
+
+
 @register_operation("OneHot")
 def _one_hot(proto):
   """Parse a OneHot Op."""

tf2jax/_src/ops_test.py

@@ -2276,6 +2276,37 @@ def div_no_nan(inputs):
     with self.subTest("check_backward_pass"):
       self.assertAllClose(jax_gradient, np.asarray(tf_gradient))
 
+  @chex.variants(with_jit=True, without_jit=True)
+  @parameterized.parameters(
+      (2., 2.), (0., 0.), (np.nan, 0.), (np.inf, 0.), (0., np.nan), (0., np.inf)
+  )
+  def test_mul_no_nan(self, x, y):
+
+    @tf.function
+    def mul_no_nan(inputs):
+      x, y = inputs
+      return tf.raw_ops.MulNoNan(x=x, y=y)
+
+    x = np.array(x)
+    y = np.array(y)
+    tf_x = tf.convert_to_tensor(x)
+    tf_y = tf.convert_to_tensor(y)
+
+    with tf.GradientTape() as g:
+      g.watch(tf_x)
+      g.watch(tf_y)
+      output = mul_no_nan([tf_x, tf_y])
+    tf_gradient = g.gradient(output, [tf_x, tf_y])
+
+    jax_func = tf2jax.convert_functional(mul_no_nan, [x, y])
+    jax_func = self.variant(jax_func)
+    jax_gradient = jax.grad(jax_func)([x, y])
+
+    with self.subTest("check_forward_pass"):
+      self.assertAllClose(jax_func([x, y]), np.asarray(output))
+    with self.subTest("check_backward_pass"):
+      self.assertAllClose(jax_gradient, np.asarray(tf_gradient))
+
   @chex.variants(with_jit=True, without_jit=True)
   def test_angle(self):
     inputs = np.array([-2.25 + 4.75j, 3.25 + 5.75j], dtype=np.csingle)