8.4.2 The online vs. offline version

• Online version
  Every call to simul refers to an execution of the forward and adjoint model. Several iterations of optimization may thus be performed within a single run of the main program (lsopt_top). The following cases may occur:
  • cold start only (no optimization)
  • cold start, followed by one or several iterations of optimization
  • warm start from previous cold start with one or several iterations
  • warm start from previous warm start with one or several iterations
• Offline version
  Every call to simul refers to a read procedure which reads the result of a forward and adjoint run Therefore, only one call to simul is allowed, itmax = 0, for cold start itmax = 1, for warm start Also, at the end, x(i+1) needs to be computed and saved to be available for the offline model and adjoint run

In order to achieve minimum difference between the online and offline code xdiff(i+1) is stored to file at the end of an (offline) iteration, but recomputed identically at the beginning of the next iteration.

Copyright © 2002 Massachusetts Institute of Technology