My_Environment

Ubuntu 14.04 LTS Japanese Remix
on VMWare Fusion v8.5.2 (4635224)
on OS X El Captian v10.11.4

GNU bash, version 4.3.11(1)-release

gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4 
(also for g++)
ADDA v.1.3b6

This article is related to ADDA (light scattering simulator based on the discrete dipole approximation).

Related: http://qiita.com/7of9/items/9537252c79f5318d8f55
Related: http://qiita.com/7of9/items/4966f131d405cd89ee07

Checkpoint file

used to stop/restart the simulation

See Section 12.5 Checkpoints of the manual.
https://github.com/adda-team/adda/blob/master/doc/manual.pdf

Stop simulation (save checkpoint)

$ ./adda -grid 25 -chp_type normal -chpoint 1s

where -grid 25 is arbitrarily added (so that the simulation should not finish within 1s).

Restart simulation (loading checkpoint)

add -chp_load parameter

$ ./adda -grid 25 -chp_type normal -chp_load -chpoint 1s

where -grid 25 is arbitrarily added (so that the simulation should not finish within 1s).

Errors in 1st/resumed simulation

1st_run

$ ./adda -grid 25 -chp_type normal -chpoint 1s
...
RE_158 = 3.2576107253E-01  -+
RE_159 = 3.2536855335E-01  -+
RE_160 = 3.2481980329E-01  -+
RE_161 = 3.2428023219E-01  -+
RE_162 = 3.2369514141E-01  -+
RE_163 = 3.2327797275E-01  -+

resumed_run

$ ./adda -grid 25 -chp_type normal -chp_load -chpoint 1s
...
RE_360 = 2.6048015704E-01  -+
RE_361 = 2.6011168142E-01  -+
RE_362 = 2.5952229833E-01  -+
RE_363 = 2.5892752389E-01  -+
RE_364 = 2.5832770551E-01  +

As you can see, the relative error (RE_XXX) becomes smaller for the resumed run which means that the checkpoint file is loaded at the resumed run.