After each solution has been computed, the result is saved as an unformatted file. The name of such a file is opt<#i>.res, where <#i> is the index number of the successful evaluation of the solution. The name of the folder in which these files are located is the base name of the sensitivities file with the suffix _optdir (for example, MyExample_optdir).

The solutions stored in the result files for successful evaluations are used as the initial solution when the new solution to compute is close to one computed previously. If the new solution to compute has already been computed, the solution is read in the appropriate file instead of the computation of the solution, and the following message is printed in the standard listing file:

 Solution is read from an old file since this solution has
  already been computed.