DOC: update documentation allowing tuple of one in reduce, etc.

1 files changed, 6 insertions, 3 deletions

diff --git a/doc/source/reference/ufuncs.rst b/doc/source/reference/ufuncs.rst
index b3fb4d384..9a8d8e20e 100644
--- a/doc/source/reference/ufuncs.rst
+++ b/doc/source/reference/ufuncs.rst
@@ -426,8 +426,8 @@ Methods
 All ufuncs have four methods. However, these methods only make sense on
 ufuncs that take two input arguments and return one output argument.
 Attempting to call these methods on other ufuncs will cause a
-:exc:`ValueError`. The reduce-like methods all take an *axis* keyword
-and a *dtype* keyword, and the arrays must all have dimension >= 1.
+:exc:`ValueError`. The reduce-like methods all take an *axis* keyword, a *dtype*
+keyword, and an *out* keyword, and the arrays must all have dimension >= 1.
 The *axis* keyword specifies the axis of the array over which the reduction
 will take place and may be negative, but must be an integer. The
 *dtype* keyword allows you to manage a very common problem that arises
@@ -443,7 +443,10 @@ mostly up to you. There is one exception: if no *dtype* is given for a
 reduction on the "add" or "multiply" operations, then if the input type is
 an integer (or Boolean) data-type and smaller than the size of the
 :class:`int_` data type, it will be internally upcast to the :class:`int_`
-(or :class:`uint`) data-type.
+(or :class:`uint`) data-type. Finally, the *out* keyword allows you to provide
+an output array (for single-output ufuncs, which are currently the only ones
+supported; for future extension, however, a tuple with a single argument
+can be passed in). If *out* is given, the *dtype* argument is ignored.
 
 Ufuncs also have a fifth method that allows in place operations to be
 performed using fancy indexing. No buffering is used on the dimensions where