CPXXaddsolnpooldivfilter and CPXaddsolnpooldivfilter

The routine CPXXaddsolnpooldivfilter/CPXaddsolnpooldivfilter adds a new diversity filter to the solution pool.

int CPXXaddsolnpooldivfilter( CPXCENVptrenv, CPXLPptrlp, doublelower_bound, doubleupper_bound, CPXDIMnzcnt, CPXDIM const *ind, double const *weight, double const *refval, char const *lname_str )

int CPXaddsolnpooldivfilter( CPXCENVptrenv, CPXLPptrlp, doublelower_bound, doubleupper_bound, intnzcnt, int const *ind, double const *weight, double const *refval, char const *lname_str )

Description

The routine CPXXaddsolnpooldivfilter/CPXaddsolnpooldivfilter adds a new diversity filter to the solution pool.

A diversity filter drives the search for multiple solutions toward new solutions that satisfy a measure of diversity specified in the filter.

This diversity measure applies only to binary variables.

Potential new solutions are compared to a reference set. You must specify which variables are to be compared. You do so with the argument ind designating the indices of variables to include in the diversity measure.

A reference set is the set of values specified by the argument refval.

You may optionally specify weights (that is, coefficients to form a linear expression in terms of the variables) in the diversity measure; if you do not specify weights, all differences between the reference set and potential new solutions will be weighted by the value 1.0 (one). CPLEX computes the diversity measure by summing the pair-wise weighted absolute differences from the reference values, like this: 


 differences(x) = sum {weight[i] times |x[ind[i]] - refval[i]|}.

A diversity filter makes sure that the solutions satisfy the constraint: 


 lower bound <= differences(x) <= upper bound

You may specify both a lower and upper bound on diversity.

In order to say, Give me solutions that are close to this one, within this specified set of variables, specify a lower_bound of 0.0 (zero) and a finite upper_bound. CPLEX then looks for solutions that differ from the reference values by at most the value of upper_bound, within the specified set of variables.

In order to say, Give me solutions that are different from this one, specify a finite lower_bound and an infinite (that is, very large) upper_bound on the diversity. CPLEX then looks for solutions that differ from the reference values by at least the value of lower_bound, within the specified set of variables.

Arguments

env
A pointer to the CPLEX environment as returned by CPXXopenCPLEX/CPXopenCPLEX.
lp
A pointer to a CPLEX problem object as returned by CPXXcreateprob/CPXcreateprob.
lower_bound
Lower bound on the diversity measure for new solutions allowed in the pool.
upper_bound
Upper bound on the diversity measure for new solutions allowed in the pool.
nzcnt
Number of variables used to define the diversity measure.
ind
An array of indices of variables in the diversity measure.
weight
An array of weights to be used in the diversity measure. The indices and corresponding weights must be stored in sequential locations in the arrays ind and weight from positions 0 (zero) to nzcnt-1. Each entry, ind[i], specifies the variable index of the corresponding weight, weight[i]. Can be NULL, in which case CPLEX uses weights of 1.0 (one).
refval
An array of reference values for the variables with indices in the array ind to compare with a solution when CPLEX computes the diversity measure.
lname_str
The name of the filter. Can be NULL.

Return

The routine returns 0 (zero) if successful and nonzero if an error occurs.

Example


 status = CPXaddsolnpooldivfilter (env, lp, loval, hival,
                                   cnt, ind, val, refval, fnamestr);