Fixed quiver to account for zero magnitude vectors

cmoad · cmoad · commit 4e795c907d90 · 2005-09-30T13:41:56.000Z
svn path=/trunk/matplotlib/; revision=1790
diff --git a/lib/matplotlib/axes.py b/lib/matplotlib/axes.py
@@ -853,10 +853,10 @@ def quiver(self, U, V, *args, **kwargs ):
         arrows = []
         N = sqrt( U**2+V**2 )
         if do_scale:
-            Nmax = maximum.reduce(maximum.reduce(N))
-            U *= (S/Nmax)
-            V *= (S/Nmax)
-            N /= Nmax
+            Nmax = maximum.reduce(maximum.reduce(N)) or 1 # account for div by zero
+            U = U*(S/Nmax)
+            V = V*(S/Nmax)
+            N = N*Nmax
 
         alpha = kwargs.get('alpha', 1.0)
         width = kwargs.get('width', 0.25)
@@ -890,7 +890,7 @@ def quiver(self, U, V, *args, **kwargs ):
             arrows,
             edgecolors = 'None',
             facecolors = (color,),
-            antialiaseds = (0,),
+            antialiaseds = (1,),
             linewidths = (width,),
             )
         if C is not None:
diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -398,7 +398,7 @@ def __init__( self, x, y, dx, dy, width=1.0, **kwargs ):
             [ 0.8, -0.1 ], [ 0.8, -0.3],
             [ 1.0,  0.0 ], [ 0.8,  0.3],
             [ 0.8,  0.1 ] ] )
-        L = sqrt(dx**2+dy**2)
+        L = sqrt(dx**2+dy**2) or 1 # account for div by zero
         arrow[:,0] *= L
         arrow[:,1] *= width
         cx = float(dx)/L
