Hi,

Apologies for the long delay in replying.  Can you give a bit of background about what you want to do?

There are two possibilities. First, you can have a numerical grid in r, th and ph.  Since the evolution equations are spatially covariant (almost; the gauge conditions are not always), you can do this, but it might not be what you really want.  Most of the Einstein Toolkit assumes that you have an x,y,z type coordinate system, so to make use of it, you probably want to express your initial data in Cartesian-type coordinates.  So, for example, if you had Kerr in Boyer-Lindquist coordinates, you would first change coordinates and basis using the usual transformation, and then evaluate the metric and extrinsic curvature on the x,y,z grid.  Is that what you want to do?