// Test if we can solve a complete optimization problem with the simplex model.
func TestPrimalSolve(t *testing.T) {
// Set up the following problem: Minimize a + 2b subject to {4 ≤ a + b
// ≤ 9, -5 ≤ 3a − b ≤ 3}.
mat := clp.NewPackedMatrix()
mat.AppendColumn([]clp.Nonzero{
{Index: 0, Value: 1.0}, // a
{Index: 1, Value: 3.0}, // 3a
})
mat.AppendColumn([]clp.Nonzero{
{Index: 0, Value: 1.0}, // b
{Index: 1, Value: -1.0}, // -b
})
rb := []clp.Bounds{
{Lower: 4, Upper: 9}, // [4, 9]
{Lower: -5, Upper: 3}, // [-5, 3]
}
obj := []float64{1.0, 2.0} // a + 2b
simp := clp.NewSimplex()
simp.LoadProblem(mat, nil, obj, rb, nil)
simp.SetOptimizationDirection(clp.Minimize)
// Solve the optimization problem.
simp.Primal(clp.NoValuesPass, clp.NoStartFinishOptions)
v := simp.ObjectiveValue()
soln := simp.PrimalColumnSolution()
// Check the results.
if !closeTo(soln[0], 1.75, 0.005) || !closeTo(soln[1], 2.25, 0.005) {
t.Fatalf("Expected [1.75 2.25] but observed %v", soln)
}
if !closeTo(v, 6.25, 0.005) {
t.Fatalf("Expected 6.25 but observed %.10g", v)
}
}
// Test if we can solve the same problem as above but with the "easy" interface.
func TestEasyPrimalSolve(t *testing.T) {
// Set up the following problem: Minimize a + 2b subject to {4 ≤ a + b
// ≤ 9, -5 ≤ 3a − b ≤ 3}.
simp := clp.NewSimplex()
simp.EasyLoadDenseProblem(
[]float64{1.0, 2.0}, // a + 2b
nil, // No explicit bounds on A or B
[][]float64{
// LB A B UB
{4.0, 1.0, 1.0, 9.0}, // 4 ≤ a + b ≤ 9
{-5.0, 3.0, -1.0, 3.0}, // -5 ≤ 3a − b ≤ 3
})
simp.SetOptimizationDirection(clp.Minimize)
// Solve the optimization problem.
simp.Primal(clp.NoValuesPass, clp.NoStartFinishOptions)
v := simp.ObjectiveValue()
soln := simp.PrimalColumnSolution()
// Check the results.
if !closeTo(soln[0], 1.75, 0.005) || !closeTo(soln[1], 2.25, 0.005) {
t.Fatalf("Expected [1.75 2.25] but observed %v", soln)
}
if !closeTo(v, 6.25, 0.005) {
t.Fatalf("Expected 6.25 but observed %.10g", v)
}
}
// Test if we can solve a problem with far more inequalities than variables.
func TestEasyManyIneqs(t *testing.T) {
// Set up the following problem: Minimize a subject to {1 ≤ a, 2 ≤ a,
// …, N ≤ a}.
const nIneqs = 100
simp := clp.NewSimplex()
inf := math.Inf(1)
ineqs := make([][]float64, nIneqs)
for i := range ineqs {
ineqs[i] = []float64{float64(i + 1), 1.0, inf}
}
simp.EasyLoadDenseProblem([]float64{1.0}, nil, ineqs)
simp.SetOptimizationDirection(clp.Minimize)
// Solve the optimization problem.
simp.Primal(clp.NoValuesPass, clp.NoStartFinishOptions)
v := simp.ObjectiveValue()
soln := simp.PrimalColumnSolution()
// Check the results.
if !closeTo(soln[0], 100.0, 0.5) {
t.Fatalf("Expected [100] but observed %v", soln)
}
if !closeTo(v, 100, 0.5) {
t.Fatalf("Expected 100 but observed %.10g", v)
}
}
// Maximize a + b subject to both 0 ≤ 2a + b ≤ 10 and 3 ≤ 2b − a ≤ 8.
func ExampleSimplex_EasyLoadDenseProblem() {
// Set up the problem.
simp := clp.NewSimplex()
simp.EasyLoadDenseProblem(
// A B
[]float64{1.0, 1.0}, // a + b
nil, // No explicit bounds on A or B
[][]float64{
// LB A B UB
{0.0, 2.0, 1.0, 10.0}, // 0 ≤ 2a + b ≤ 10
{3.0, -1.0, 2.0, 8.0}, // 3 ≤ -a + 2b ≤ 8
})
simp.SetOptimizationDirection(clp.Maximize)
// Solve the optimization problem.
simp.Primal(clp.NoValuesPass, clp.NoStartFinishOptions)
val := simp.ObjectiveValue()
soln := simp.PrimalColumnSolution()
// Output the results.
fmt.Printf("a = %.1f\nb = %.1f\na + b = %.1f\n", soln[0], soln[1], val)
// Output:
// a = 2.4
// b = 5.2
// a + b = 7.6
}
// Maximize a + b subject to both 0 ≤ 2a + b ≤ 10 and 3 ≤ 2b − a ≤ 8.
func ExampleSimplex_LoadProblem() {
// Set up the problem.
mat := clp.NewPackedMatrix()
mat.AppendColumn([]clp.Nonzero{
{Index: 0, Value: 2.0}, // 2a
{Index: 1, Value: -1.0}, // -a
})
mat.AppendColumn([]clp.Nonzero{
{Index: 0, Value: 1.0}, // b
{Index: 1, Value: 2.0}, // 2b
})
rb := []clp.Bounds{
{Lower: 0, Upper: 10}, // [0, 10]
{Lower: 3, Upper: 8}, // [3, 8]
}
obj := []float64{1.0, 1.0} // a + b
simp := clp.NewSimplex()
simp.LoadProblem(mat, nil, obj, rb, nil)
simp.SetOptimizationDirection(clp.Maximize)
// Solve the optimization problem.
simp.Primal(clp.NoValuesPass, clp.NoStartFinishOptions)
val := simp.ObjectiveValue()
soln := simp.PrimalColumnSolution()
// Output the results.
fmt.Printf("a = %.1f\nb = %.1f\na + b = %.1f\n", soln[0], soln[1], val)
// Output:
// a = 2.4
// b = 5.2
// a + b = 7.6
}
// Ensure that we can both query and change the primal tolerance used in a
// simplex model.
func TestGetSetSimplexPrimalTolerance(t *testing.T) {
simp := clp.NewSimplex()
initial := simp.PrimalTolerance()
simp.SetPrimalTolerance(initial * 2.0)
reset := simp.PrimalTolerance()
if reset != initial*2.0 {
t.Fatalf("Expected %f but observed %f", initial*2.0, reset)
}
}
// Test if we can load a problem into a simplex model.
func TestLoadProblem(t *testing.T) {
s := clp.NewSimplex()
m := clp.NewPackedMatrix()
s.LoadProblem(m, nil, nil, nil, nil)
}
// Test if we can create a simplex model.
func TestCreateSimplex(t *testing.T) {
_ = clp.NewSimplex()
}
