ILOG CPLEX users can vary parameters by means of the set command. This command is used to set ILOG CPLEX parameters to values different from their default values. The procedure for setting a parameter is similar to that of other commands. Commands can be carried out incrementally or all in one line from the CPLEX> prompt. Whenever a parameter is set to a new value, ILOG CPLEX inserts a comment in the log file that indicates the new value.

Setting a Parameter

To see the parameters that can be changed, type:

The parameters that can be changed are displayed with a prompt, like this:

Available Parameters:

advance       set indicator for advanced starting information
barrier       set parameters for barrier optimization
clocktype     set type of clock used to measure time
conflict      set parameters for finding conflicts
defaults      set all parameter values to defaults
emphasis      set optimization emphasis
feasopt       set parameters for feasopt
logfile       set file to which results are printed
lpmethod      set method for linear optimization
mip           set parameters for mixed integer optimization
network       set parameters for network optimizations
output        set extent and destinations of outputs
parallel      set parallel optimization mode
preprocessing set parameters for preprocessing
qpmethod      set method for quadratic optimization
read          set problem read parameters
sifting       set parameters for sifting optimization
simplex       set parameters for primal, dual simplex optimizations
threads       set default parallel thread count
timelimit     set time limit in seconds
tune          set parameters for parameter tuning
workdir       set directory for working files
workmem       set memory available for working storage (megabytes)

Parameter to set:

If you press the <return> key without entering a parameter name, the following message is displayed:

No parameters changed.

Resetting Defaults

After making parameter changes, it is possible to reset all parameters to default values by issuing one command:

This resets all parameters to their default values, except for the name of the log file.

Summary

The general syntax for the set command is:

Displaying Parameter Settings

The current values of the parameters can be displayed with the command:

A list of parameters with settings that differ from the default values can be displayed with the command:

For a description of all parameters and their default values, see the reference manual ILOG CPLEX Parameters.

ILOG CPLEX also accepts customized system parameter settings via a parameter specification file. See the reference manual ILOG CPLEX File Formats for a description of the parameter specification file and its use.