From 3a698d6e7d972d2c18fe4d2524e92ff637326f88 Mon Sep 17 00:00:00 2001
From: Rasmus Diederichsen <rasmus@peltarion.com>
Date: Thu, 8 Nov 2018 16:23:36 +0100
Subject: [PATCH] Add note to errorbar function about sign of errors

---
 lib/matplotlib/axes/_axes.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 2e1c59fd5ea6..9037674780e2 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -2950,6 +2950,8 @@ def errorbar(self, x, y, yerr=None, xerr=None,
                 upper errors.
             - *None*: No errorbar.
 
+            Note that all error arrays should have *positive* values.
+
             See :doc:`/gallery/statistics/errorbar_features`
             for an example on the usage of ``xerr`` and ``yerr``.