MIP node log display information

Purpose

MIP node log display information

Description

Decides what CPLEX reports to the screen and records in a log during mixed integer optimization (MIP).

The amount of information displayed increases with increasing values of this parameter.

• A setting of 0 (zero) causes no node log to be displayed until the optimal solution is found.

• A setting of 1 (one) displays an entry for each integer feasible solution found.

  Each entry contains:

  • the value of the objective function;

  • the node count;

  • the number of unexplored nodes in the tree;

  • the current optimality gap.

• A setting of 2 also generates an entry at a frequency determined by the MIP node log interval parameter. At a lower frequency, the log additionally displays elapsed time in seconds and deterministic time in ticks.

• A setting of 3 gives all the information of option 2 plus additional information:

  • At the same frequency as option 2, the node log adds a line specifying the number of cutting planes added to the problem since the last node log line was displayed; this additional line is omitted if the number of cuts added since the last log line is 0 (zero).
  • Whenever a MIP start was successfully used to find a new incumbent solution, that success is recorded in the node log. (This information about MIP starts is independent of the MIP interval frequency in option 2.)
  • For each new incumbent that is found, the node log displays how much time in seconds and how many deterministic ticks elapsed since the beginning of optimization. (This information about elapsed time between new incumbents is independent of the MIP interval frequency in option 2.)

• A setting of 4 additionally generates entries for the LP root relaxation according to the setting of the parameter to control the simplex iteration information display (SimDisplay, CPX_PARAM_SIMDISPLAY).

• A setting of 5 additionally generates entries for the LP subproblems, also according to the setting of the parameter to control the simplex iteration information display (SimDisplay, CPX_PARAM_SIMDISPLAY).

See also

MIP node log interval, simplex iteration information display, network logging display switch, and messages to screen switch