Setting CPLEX parameters

The set command controls CPLEX parameters in the Interactive Optimizer.

CPLEX users can vary parameters by means of the set command. This command is used to set 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, 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:

set

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
dettimelimit    set deterministic time limit in ticks
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
randomseed      set seed to initialize the random number generator
read            set problem read parameters
sifting         set parameters for sifting optimization
simplex         set parameters for primal and dual simplex optimizations
solutiontarget  set type of solution CPLEX will attempt to compute
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:

set defaults

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:

set parameter option new_value

Displaying parameter settings

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

display settings all

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

display settings changed

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

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