Update c api documentation

2 files changed, 28 insertions, 0 deletions

diff --git a/doc/release/1.8.0-notes.rst b/doc/release/1.8.0-notes.rst
index c5c9d6e8d..e65658ad3 100644
--- a/doc/release/1.8.0-notes.rst
+++ b/doc/release/1.8.0-notes.rst
@@ -159,3 +159,21 @@ General
 Use of non-integer indices has been deprecated. Previously float indices
 were truncated to integers without warning.
 
+C-API
+~~~~~
+
+New Features
+============
+
+When creating a ufunc, the default ufunc operand flags can be overridden
+via the new op_flags attribute of the ufunc object. For example, to set
+the operand flag for the first input to read/write:
+
+PyObject \*ufunc = PyUFunc_FromFuncAndData(...);
+ufunc->op_flags[0] = NPY_ITER_READWRITE;
+
+This allows a ufunc to perform an operation in place. Also, global nditer flags
+can be overridden via the new iter_flags attribute of the ufunc object.
+For example, to set the reduce flag for a ufunc:
+
+ufunc->iter_flags = NPY_ITER_REDUCE_OK;
diff --git a/doc/source/reference/c-api.types-and-structures.rst b/doc/source/reference/c-api.types-and-structures.rst
index 07c7e07be..79a888912 100644
--- a/doc/source/reference/c-api.types-and-structures.rst
+++ b/doc/source/reference/c-api.types-and-structures.rst
@@ -652,6 +652,8 @@ PyUFunc_Type
           void *ptr;
           PyObject *obj;
           PyObject *userloops;
+          npy_uint32 *op_flags;
+          npy_uint32 *iter_flags;
       } PyUFuncObject;
 
    .. cmacro:: PyUFuncObject.PyObject_HEAD
@@ -755,6 +757,14 @@ PyUFunc_Type
        numbers are always larger than :cdata:`NPY_USERDEF`.
 
 
+   .. cmember:: npy_uint32 PyUFuncObject.op_flags
+
+       Override the default operand flags for each ufunc operand.
+
+   .. cmember:: npy_uint32 PyUFuncObject.iter_flags
+
+       Override the default nditer flags for the ufunc.
+
 PyArrayIter_Type
 ----------------