Hello Erik, > This is almost possible. For puncture data, one typically evolves > lapse, shift, and a quantity B (the time derivative of the shift). For > Kerr-Schild data, one also needs to evolve A, the time derivative of > the lapse. Otherwise, Kerr-Schild data are not stationary. (One could > instead add an offset alpha_0 to the evolution equations for K, but > that is quite non-standard and not implemented in McLachlan.) Ok so it is possible.
> Additionally, I find it convenient to smooth all quantities near the > singularity, and to choose to advect both lapse and shift. I don't > know whether the latter is necessary in theory, but I am always using > it. Concerning the smoothing it seems that some smoothing was necessary to not crash the code (via the Exact epsilon parameter to transform r -> r+epsilon). An alternative may have been to use NoExcision to fill the interior of the AH with smooth data. > I can send a sample parameter file if that helps. That would be great if you had something that you could send around easily. Yours, Roland -- My email is as private as my paper mail. I therefore support encrypting and signing email messages. Get my PGP key from http://pgp.mit.edu .
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