SAV file format: numerically accurate binary files

CPLEX supports the SAV binary file format for numerical accuracy in reading and writing problems.

SAV is a binary file format specific to CPLEX. This format is efficient for fast reading and writing of models and associated basis information. For example, it can effectively reduce read and write time for problems that are solved repetitively.

Tip: CPLEX includes the basis in a SAV file only if the problem currently in memory has been optimized and a basis exists.

This format also offers the advantage of being numerically accurate (to the same degree as your platform) in contrast to text file formats that may lose numerical accuracy. In other words, it provides a greater degree of precision in data. However, since a SAV file is binary, you cannot read nor edit it with your favorite text editor.

These other, more specialized file formats are based on the SAV file format:

• DPE is the format CPLEX uses to write a problem in a binary SAV file after the objective function of the problem has been perturbed.
• PPE is the format CPLEX uses to write a problem in a binary SAV file after the righthand side (RHS) has been perturbed.
• PRE is the format CPLEX uses to write a presolved, reduced problem formulation to a binary SAV file. Since a presolved problem has been reduced, it does not correspond to the original problem.

The topic Saving problems in the Interactive Optimizer explains how to use the SAV file format in the Interactive Optimizer.