Purpose
Initiates the search for
Irreducible Infeasible Sets (IIS) amongst problems which are linear
infeasible.
Synopsis
int XPRS_CC XPRSiis(XPRSprob prob, const char *flags);
IIS [-flags]
Arguments
|
prob
|
The current problem.
|
|
flags
|
Flags to pass to XPRSiis (IIS). Can be set to the following:
|
o
|
display IIS information and optimization process logs on screen;
|
|
f
|
write IIS information into a file problem_name.iis.
|
If no flags are set, only the IIS information will be displayed to the screen.
|
Related Controls
Integer
|
|
Number of Irreducible Infeasible Sets to be found.
|
Example 1 (Library)
This example searches for IISs and then questions the problem attribute
NUMIIS to determine how many were found:
int iis;
...
XPRSiis(prob,"f");
XPRSgetintattrib(prob, XPRS_NUMIIS, &iis);
printf("number of IISs = %d\n", iis);
Example 2 (Console)
Calling the command on its own begins a search for as many IISs as have been specified by the
control
MAXIIS:
Further information
1. A model may have several infeasibilities. Repairing a single IIS may not make
the model feasible. For this reason the Optimizer can find an IIS for each of the infeasibilities
in a model. If the control
MAXIIS is set to a positive integer value
then the
XPRSiis (
IIS) command will stop if
MAXIIS IISs have been found.
By default the control
MAXIIS is set to
-1, in which case an IIS is found for each
of the independent infeasibilities in the model.
2. The problem attribute,
NUMIIS, allows the user to
recover the number of IISs found in a particular search. See Example 1 for details
of this.
Related topics
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