Add docs

chainerx/_docs/routines.py

@@ -579,6 +579,23 @@ def _docs_indexing():
 .. seealso:: :func:`numpy.where`
 """)
 
+    _docs.set_doc(
+        chainerx.nonzero,
+        """nonzero(a)
+Return the indices of the elements that are non-zero.
+
+Args:
+    a (~chainerx.ndarray): Input array.
+
+Returns:
+    tuple of :func:`~chainerx.ndarray`: Indices of elements that are non-zero.
+
+Note:
+    During backpropagation, this function does not propagate gradients.
+
+.. seealso:: :func:`numpy.nonzero`
+""")
+
 
 def _docs_linalg():
     _docs.set_doc(

docs/source/chainerx/reference/routines.rst

@@ -105,6 +105,7 @@ Indexing routines
 
    chainerx.take
    chainerx.where
+   chainerx.nonzero
 
 Linear algebra
 --------------