title: griddata scipy interpolation not working (giving nan)
body: <p>I was trying out the 2d example given in the scipy.interpolation.griddata  help file.
  It works for interpolation with 'nearest'. But it gives a matrix filled with nan while using any other interpolation like 'linear' or 'cubic'. If I give the argument fill_value=5 , it gives the matrix filled with 5.</p>
  
  <p>Is this due to some installation problem? </p>
  
  <p>I was trying the exact same thing they have given in the help document.
  But somehow it is giving the result as if the points i asked to interpolating is lying outside the input points. (which is not!! I followed the example)</p>
  
  <p>I shall post the example to reproduce the error (taken form doc)</p>
  
  <pre><code>def func(x, y):
      return x*(1-x)*np.cos(4*np.pi*x) * np.sin(4*np.pi*y**2)**2
  
  grid_x, grid_y = np.mgrid[0:1:10j, 0:1:10j]
  points = np.random.rand(100, 2)
  values = func(points[:,0], points[:,1])
  
  from scipy.interpolate import griddata
  
  grid_z0 = griddata(points, values, (grid_x, grid_y), method='nearest')
  grid_z1 = griddata(points, values, (grid_x, grid_y), method='linear')
  grid_z2 = griddata(points, values, (grid_x, grid_y), method='cubic')
  </code></pre>
  
  <p>I am getting grid_z1 and grid_z2 to be a matrix filled with nan.</p>
  
  <p><strong>UPDATE</strong> : I installed all the packages in another Ubuntu 11.10 machine. And the same script gave perfectly correct answer. Previously I was trying on Porteus distro (live slackware family). Hence I think i can safely conclude that this was some problem in my installation. Anybody have any idea what could have gone wrong? Does any library conflict result in this kind of behavior? Since my main machine is Portues, i have no other option than to repair the scipy in it.</p>