[Users] problems with AHFinderDirect

[Eloisa Bentivegna]

On Jun 14, 2012, at 4:34 PM, Ian Hinder wrote:

>>>> this error usually comes up when the arguments to umfpack_numeric() are not numbers (as would happen, for instance, if the metric had become singular). Could you check that your 3+1 variables are finite? Thorn NaNChecker could help you do that.
>>> 
>>> If this turns out to be the problem, we should probably check for this in AHFinderDirect and give an error message.  Something like "The metric has become singular at [x,y,z]; unable to compute horizon and aborting the run".
>> 
>> Nah: "unable to compute horizon; continuing the run".
> 
> This would be consistent with the behaviour when it is unable to find the horizon for other reasons, so I agree.  Though it might be good to have a "strict" parameter for each horizon which insists that it must be found when it is searched for, or the run stops.  Not sure what to do about horizons disappearing at a merger though.

Well, that is heavily case-dependent. A user will need to decide by themselves whether finding a horizon is absolutely necessary, and when. Maybe we could introduce parameters strict_after and strict_before, similarly to the existing find_after and find_before?

Eloisa