griddata usage

Hello all

Can any one explain me how can I use griddata in matplotlib for 2-d interpolation of polar to cartesian co-ordinates.
I have two 1D arrays r and theta of 128 and 64 cells respectively
I have a 2D array temperature T(r,theta) with (128, 64) cells. I would like to have Tnew(200,200) cells in cartesian coordinates x = r*cos(th) and y = r*sin(th)

for the same I use

Tnew = griddata(x,y,T,xi,yi) ....

and x = outer(r,cos(th)) and y=outer(r,sin(th))
where xi,yi = mgrid[x.min():x.max():200j,y.min():y.max():200j]

I get a ValueError suggesting that griddata does not like to have 2D arrays of x and y

How can I get this to work?

Bhargav Vaidya