Class LinearOptimizationSolution

AI-generated Key Takeaways

• LinearOptimizationSolution represents the solution of a linear program, providing methods to access solution details.

• It allows retrieval of the objective function's value, solution status, and individual variable values.

• The provided example demonstrates solving a linear program with two variables and constraints, maximizing a given objective function.

• isValid() method helps determine if the solution is feasible or optimal, while getStatus() provides detailed solution status information.

• getVariableValue() allows access to the specific values assigned to variables in the solution.

LinearOptimizationSolution

The solution of a linear program. The example below solves the following linear program:

Two variables, x and y:
0 ≤ x ≤ 10
0 ≤ y ≤ 5

Constraints:
0 ≤ 2 * x + 5 * y ≤ 10
0 ≤ 10 * x + 3 * y ≤ 20

Objective:
Maximize x + y

const engine = LinearOptimizationService.createEngine();

// Add variables, constraints and define the objective with addVariable(),
// addConstraint(), etc. Add two variables, 0 <= x <= 10 and 0 <= y <= 5
engine.addVariable('x', 0, 10);
engine.addVariable('y', 0, 5);

// Create the constraint: 0 <= 2 * x + 5 * y <= 10
let constraint = engine.addConstraint(0, 10);
constraint.setCoefficient('x', 2);
constraint.setCoefficient('y', 5);

// Create the constraint: 0 <= 10 * x + 3 * y <= 20
constraint = engine.addConstraint(0, 20);
constraint.setCoefficient('x', 10);
constraint.setCoefficient('y', 3);

// Set the objective to be x + y
engine.setObjectiveCoefficient('x', 1);
engine.setObjectiveCoefficient('y', 1);

// Engine should maximize the objective
engine.setMaximization();

// Solve the linear program
const solution = engine.solve();
if (!solution.isValid()) {
  Logger.log(`No solution ${solution.getStatus()}`);
} else {
  Logger.log(`Objective  value: ${solution.getObjectiveValue()}`);
  Logger.log(`Value of x: ${solution.getVariableValue('x')}`);
  Logger.log(`Value of y: ${solution.getVariableValue('y')}`);
}

Methods

Method	Return type	Brief description
getObjectiveValue()	Number	Gets the value of the objective function in the current solution.
getStatus()	Status	Gets the status of the solution.
getVariableValue(variableName)	Number	Gets the value of a variable in the solution created by the last call to LinearOptimizationEngine.solve().
isValid()	Boolean	Determines whether the solution is either feasible or optimal.

Detailed documentation

getObjectiveValue()

Gets the value of the objective function in the current solution.

const engine = LinearOptimizationService.createEngine();

// Add variables, constraints and define the objective with addVariable(),
// addConstraint(), etc
engine.addVariable('x', 0, 10);

// ...

// Solve the linear program
const solution = engine.solve();
Logger.log(`ObjectiveValue: ${solution.getObjectiveValue()}`);

Return

Number — the value of the objective function

---

getStatus()

Gets the status of the solution. Before solving a problem, the status will be NOT_SOLVED.

const engine = LinearOptimizationService.createEngine();

// Add variables, constraints and define the objective with addVariable(),
// addConstraint(), etc
engine.addVariable('x', 0, 10);

// ...

// Solve the linear program
const solution = engine.solve();
const status = solution.getStatus();

if (status !== LinearOptimizationService.Status.FEASIBLE &&
    status !== LinearOptimizationService.Status.OPTIMAL) {
  throw `No solution ${status}`;
}
Logger.log(`Status: ${status}`);

Return

Status — the status of the solver

---

getVariableValue(variableName)

Gets the value of a variable in the solution created by the last call to LinearOptimizationEngine.solve().

const engine = LinearOptimizationService.createEngine();

// Add variables, constraints and define the objective with addVariable(),
// addConstraint(), etc
engine.addVariable('x', 0, 10);

// ...

// Solve the linear program
const solution = engine.solve();
Logger.log(`Value of x: ${solution.getVariableValue('x')}`);

Parameters

Name	Type	Description
variableName	String	name of the variable

Return

Number — the value of the variable in the solution

---

isValid()

Determines whether the solution is either feasible or optimal.

const engine = LinearOptimizationService.createEngine();

// Add variables, constraints and define the objective with addVariable(),
// addConstraint(), etc
engine.addVariable('x', 0, 10);

// ...

// Solve the linear program
const solution = engine.solve();
if (!solution.isValid()) {
  throw `No solution ${solution.getStatus()}`;
}

Return

Boolean — true if the solution is valid (Status.FEASIBLE or Status.OPTIMAL); false if not