Hi all,

this hopefully is a dumb question, but I cannot for the life of me get access to the x,y,z,r coordinates defined in CartGrid3D.

Suppose I have a thorn X that wants to access these coordinates from test.cc, then the thorn should inherit: grid, the .cc should #include "cctk_Arguments.h" and the line that accesses, say x[0], should be called after DECLARE_CCTK_ARGUMENTS.

Unfortunately doing this results in an error:

[maths02:86267] *** Process received signal ***
[maths02:86267] Signal: Segmentation fault (11)
[maths02:86267] Signal code: Address not mapped (1)
[maths02:86267] Failing at address: (nil)

Which is analogous to the error message you get by defining a grid variable in interface.ccl without the accompanying STORAGE: in schedule.ccl, i.e. the memory is not allocated.

I am using Llama as my coordinate system, but I know this basically is a wrapper for CartGrid3D and these coordinates are still set. I see the printout from CartGrid3D.

I try to access these coordinates at, for example, CCTK_INITIAL, when the grid structure is already setup. I have also tried later time bins such as CCTK_POSTSTEP.

Example files that access these coordinates are:

CTGBase::debug.cc

ADMDerivatives::calc_derivs.cc

Coordinates::cylinderinbox.cc

However I am not having any luck reverse-engineering these.

Any ideas would be appreciated.

Chris