In the releases prior to ET_2020_05 I was able to evolve grid arrays using RK4 with a kludge algorithm coupled to MoL. (The issue with MoL and grid arrays is that Mol attempts to updates the arrays for all components of the grid owned by that process. The kludge was to check to see that if the "correct" component is being updated, and if not, re-write the old values of the grid array). I used this to evolve geodesics and the puncture locations. From ET_2020_05, I get the error

terminate called after throwing an instance of 'std::out_of_range' what(): vector::_M_range_check

1. CarpetLib::signal_handler(int) [./cactus_test(_ZN9CarpetLib14signal_handlerEi+0xf4) [0x6b1c74]]
2. /lib64/libc.so.6(+0x35270) [0x7f4fbc077270]
3. /lib64/libc.so.6(gsignal+0x37) [0x7f4fbc0771f7]
4. /lib64/libc.so.6(abort+0x148) [0x7f4fbc0788e8]
5. __gnu_cxx::__verbose_terminate_handler() [/lib64/libstdc++.so.6(_ZN9__gnu_cxx27__verbose_terminate_handlerEv+0x165) [0x7f4fbca9bac5]]
6. /lib64/libstdc++.so.6(+0x5ea36) [0x7f4fbca99a36]
7. /lib64/libstdc++.so.6(+0x5ea63) [0x7f4fbca99a63]
8. /lib64/libstdc++.so.6(+0x5ec83) [0x7f4fbca99c83]
9. std::__throw_out_of_range(char const*) [/lib64/libstdc++.so.6(_ZSt20__throw_out_of_rangePKc+0x77) [0x7f4fbcaeea97]]
10. Carpet::PoisonGroup(_cGH const*, int, Carpet::checktimes) [./cactus_test(_ZN6Carpet11PoisonGroupEPK4_cGHiNS_10checktimesE+0x551) [0x5241f1]]
11. Carpet::Poison(_cGH const*, Carpet::checktimes, int) [./cactus_test(_ZN6Carpet6PoisonEPK4_cGHNS_10checktimesEi+0xcd) [0x523bbd]]
12. ./cactus_test() [0x51881d]
13. Carpet::Evolve(tFleshConfig*) [./cactus_test(_ZN6Carpet6EvolveEP12tFleshConfig+0x191) [0x5162e1]]
14. ./cactus_test(main+0xa5) [0xd560e5]
15. /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f4fbc063c05]
16. ./cactus_test() [0x4b6ce9]

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2534/evolution-of-grid-arrays-with-mol-no