[Matplotlib-users] Matplotlib or numpy bug?

[Jesper L. <jes...@gm...>]

Hi matplotlib users,

The script below produces weird arrows when using numpy 1.2.1 and
matplotlib trunk. When I reinstall numpy 1.2.0 instead it seems fine.
I use the Agg backend. I am not sure where to start in tracking the
bug down so I will just post the rather sparse information that I
have.

Please let me know if you need any further information from me.

Best regards,
Jesper

import math
import numpy.ma as ma
import pylab as p

a = ma.ones((10,10))
a[:2,:] = ma.masked
a[:,9:] = ma.masked
b = ma.array(-a)
nx, ny = a.shape

for i in range(nx):
  for j in range(ny):
    a[i,j] = a[i,j]*math.cos(i*j)
    b[i,j] = -b[i,j]*math.sin(i*j)

print a

p.quiver(a,b)
p.grid(True)
p.savefig('test1.png')