com.dashoptimization

Class XPRBcut

java.lang.Object

com.dashoptimization.XPRBcut

public class XPRBcut
extends java.lang.Object

This class represents a cut definition in BCL. All terms in a cut must belong to the same problem as the cut itself.

Method Summary

Modifier and Type	Method and Description
void	add(double val)
void	add(XPRBexpr l) Add a linear expression to a cut.
void	add(XPRBvar var)
void	addTerm(double val) Add a constant term to a cut.
void	addTerm(double val, XPRBvar var)
void	addTerm(XPRBvar var)
void	addTerm(XPRBvar var, double val) Add a variable term to a cut.
void	assign(XPRBrelation lr) Assign a linear relation to a cut.
void	delTerm(XPRBvar var) Delete a variable term from a cut.
int	getID() Get the ID of a cut.
double	getRHS() Get the RHS value (= constant term) of a cut.
int	getType() Get the type of a cut.
boolean	isValid() Test whether a cut is correctly defined.
void	print() Print out a cut.
void	setID(int val) Set the cut ID value.
void	setTerm(double val) Set the constant term (= RHS value) of a cut.
void	setTerm(double val, XPRBvar var)
void	setTerm(XPRBvar var, double val) Set a cut term.
void	setType(int type) Set the cut row type.
java.lang.String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

isValid

public boolean isValid()

Test whether a cut is correctly defined.

     XPRBcut cut1;
     if(cut1.isValid() == false)
        System.out.println("Error in cut definition.");
 

assign

public void assign(XPRBrelation lr)
            throws java.lang.ArithmeticException

Assign a linear relation to a cut.

     XPRBprob expl2;
     XPRBvar x1, x2;
     XPRBrelation lr;
     XPRBcut cut5;
     expl2 = new XPRBprob("example2");
     x1 = expl2.newVar("abc3", XPRB.UI, 1, 100);
     x2 = expl2.newVar("abc1", XPRB.PL, 0, XPRB.INFINITY);
     lr = x2.gEql(x1);
     cut5.assign(lr);
 

Parameters:

lr - linear relation

Throws:

java.lang.ArithmeticException - If the relation is not linear.

setType

public void setType(int type)

Set the cut row type. This method changes the type of a previously defined cut to inequality or equation.

     XPRBprob expl2;
     XPRBcut cut1;
     expl2 = new XPRBprob("example2");
     cut1 = expl2.newCut(1);
     cut1.setType(XPRB.E);
 

Parameters:

type - Constraint type. Possible values:

• XPRB.L <= (inequality)
• XPRB.G >= (inequality)
• XPRB.E = (equation)

setID

public void setID(int val)

Set the cut ID value. This method changes the ID value of a previously defined cut. The cut ID can be chosen freely by the user to identify or classify (groups of) cuts.

     XPRBprob expl2;
     XPRBcut cut1;
     expl2 = new XPRBprob("example2");
     cut1 = expl2.newCut();
     cut1.setID(10);
 

Parameters:

val - Cut ID value.

getRHS

public double getRHS()

Get the RHS value (= constant term) of a cut. The default RHS value is 0.

     XPRBprob expl2;
     XPRBcut cut1;
     double rhs;
     expl2 = new XPRBprob("example2");
     cut1 = expl2.newCut(1);
     rhs = cut1.getRHS();
 

Returns:

Right hand side (RHS) value (default 0)

getType

public int getType()

Get the type of a cut.

     XPRBprob expl2;
     XPRBcut cut1;
     int rtype;
     expl2 = new XPRBprob("example2");
     cut1 = expl2.newCut(1);
     rtype = cut1.getType();
 

Returns:

Constraint type. Possible values:

• XPRB.L <= (inequality)
• XPRB.G >= (inequality)
• XPRB.E = (equation)
• -1 an error has occurred

getID

public int getID()

Get the ID of a cut. The default ID value is 0.

     XPRBprob expl2;
     XPRBcut cut1;
     int val;
     expl2 = new XPRBprob("example2");
     cut1 = expl2.newCut(1);
     val = cut1.getID();
 

Returns:

Cut ID value.

setTerm

public void setTerm(XPRBvar var,
                    double val)

Set a cut term. This method sets the coefficient of a given variable to the value coeff.

     XPRBprob expl2;
     XPRBcut cut1;
     XPRBvar x1;
     expl2 = new XPRBprob("example2");
     x1 = expl2.newVar("abc3", XPRB.UI, 1, 100);
     cut1 = expl2.newCut(1);
     cut1.setTerm(x1, 5.4);
 

Parameters:

var - variable of type XPRBvar

val - value of the coefficient of the variable var

setTerm

public void setTerm(double val)

Set the constant term (= RHS value) of a cut. The RHS of the cut is set to the given constant.

     XPRBprob expl2;
     XPRBcut cut1;
     expl2 = new XPRBprob("example2");
     cut1 = expl2.newCut(1);
     cut1.setTerm(7);
 

Parameters:

val - constant term (RHS value)

setTerm

public void setTerm(double val,
                    XPRBvar var)

See Also:

setTerm(var, val)

addTerm

public void addTerm(XPRBvar var,
                    double val)

Add a variable term to a cut. This method adds a new term to a cut, comprising the variable var with coefficient coeff. If the cut already has a term with variable var, coeff is added to its coefficient.

     XPRBprob expl2;
     XPRBcut cut1;
     XPRBvar x1;
     expl2 = new XPRBprob("example2");
     x1 = expl2.newVar("abc3", XPRB.UI, 1, 100);
     cut1 = expl2.newCut(1);
     cut1.addTerm(x1, 5.4);
 

Parameters:

var - variable of type XPRBvar

val - value to be added to the coefficient of the variable var

addTerm

public void addTerm(double val,
                    XPRBvar var)

See Also:

addTerm(var, val)

addTerm

public void addTerm(XPRBvar var)

See Also:

addTerm(var, 1)

addTerm

public void addTerm(double val)

Add a constant term to a cut. The given constant term is added to the RHS value of the cut.

     XPRBprob expl2;
     XPRBcut cut1;
     expl2 = new XPRBprob("example2");
     cut1 = expl2.newCut(1);
     cut1.addTerm(7);
 

Parameters:

val - value to be added to the RHS of the cut

delTerm

public void delTerm(XPRBvar var)

Delete a variable term from a cut.

     XPRBprob expl2;
     XPRBcut cut1;
     XPRBvar x1;
     expl2 = new XPRBprob("example2");
     x1 = expl2.newVar("abc3", XPRB.UI, 1, 100);
     cut1 = expl2.newCut(1);
     cut1.addTerm(x1, 5.4);
     cut1.delTerm(x1);
 

Parameters:

var - variable of type XPRBvar

add

public void add(XPRBexpr l)
         throws java.lang.ArithmeticException

Add a linear expression to a cut. The entire linear expression given is added to the left hand side of the cut. That is, in order to normalize the cut representation, any constant term contained in the linear expression will be subtracted from the RHS value.

     XPRBprob expl2;
     XPRBcut cut1;
     XPRBvar x1;
     expl2 = new XPRBprob("example2");
     x1 = expl2.newVar("abc3", XPRB.UI, 1, 100);
     cut1 = expl2.newCut(1);
     cut1.add(x1.add(17));
 

Parameters:

l - linear expression of type XPRBexpr

Throws:

java.lang.ArithmeticException - If the relation is not linear.

add

public void add(XPRBvar var)

See Also:

addTerm(var, 1)

add

public void add(double val)

See Also:

addTerm(val)

print

public void print()

Print out a cut. This method prints out a cut in LP-format.

     XPRBprob expl2;
     XPRBcut ctr2;
     XPRBvar x4[5];
     XPRBcut ctr2;
     int i;
     for(i=0;i<5;i++) x4[i] = expl2.newVar("x4", XPRB.PL, 0, 500);
     ctr2 = expl2.newCtr("r2", x4[0].add(x4[1]).eql(9));
     ctr2.print();
 

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

See Also:

getID()