From b8a0dcf308dec9bc1dc90bbebf54611f56c781d6 Mon Sep 17 00:00:00 2001
From: Michael Droettboom <mdboom@gmail.com>
Date: Mon, 13 May 2013 17:46:37 -0400
Subject: [PATCH] Fix #1999: dash value of zero causes infinite loop

---
 lib/matplotlib/backend_bases.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
index 52190fe0295f..e950ea335a8f 100644
--- a/lib/matplotlib/backend_bases.py
+++ b/lib/matplotlib/backend_bases.py
@@ -872,6 +872,10 @@ def set_dashes(self, dash_offset, dash_list):
             specifies the on-off sequence as points.  ``(None, None)`` specifies a solid line
 
         """
+        if dash_list is not None:
+            dash_list = np.asarray(dash_list)
+            if np.any(dash_list <= 0.0):
+                raise ValueError("All values in the dash list must be positive")
         self._dashes = dash_offset, dash_list
 
     def set_foreground(self, fg, isRGB=False):