def test_2dof_surface_opt(self):
"""
Optimize the minor radius and elongation of an axisymmetric torus to
obtain a desired volume and area.
"""
for solver in solvers:
desired_volume = 0.6
desired_area = 8.0
# Start with a default surface, which is axisymmetric with major
# radius 1 and minor radius 0.1.
surf = SurfaceRZFourier(quadpoints_phi=62, quadpoints_theta=63)
# Set initial surface shape. It helps to make zs(1,0) larger
# than rc(1,0) since there are two solutions to this
# optimization problem, and for testing we want to find one
# rather than the other.
surf.set_zs(1, 0, 0.2)
# Parameters are all non-fixed by default, meaning they will be
# optimized. You can choose to exclude any subset of the variables
# from the space of independent variables by setting their 'fixed'
# property to True.
surf.set_fixed('rc(0,0)')
# Each function you want in the objective function is then
# equipped with a shift and weight, to become a term in a
# least-squares objective function. A list of terms are
# combined to form a nonlinear-least-squares problem.
prob = LeastSquaresProblem([(surf.volume, desired_volume, 1),
(surf.area, desired_area, 1)])
# Verify the state vector and names are what we expect
np.testing.assert_allclose(prob.x, [0.1, 0.2])
self.assertEqual(prob.dofs.names[0][:28],
'rc(1,0) of SurfaceRZFourier ')
self.assertEqual(prob.dofs.names[1][:28],
'zs(1,0) of SurfaceRZFourier ')
# Solve the minimization problem:
solver(prob)
# Check results
self.assertAlmostEqual(surf.get_rc(0, 0), 1.0, places=13)
self.assertAlmostEqual(surf.get_rc(1, 0),
0.10962565115956417,
places=13)
self.assertAlmostEqual(surf.get_zs(0, 0), 0.0, places=13)
self.assertAlmostEqual(surf.get_zs(1, 0),
0.27727411213693337,
places=13)
self.assertAlmostEqual(surf.volume(), desired_volume, places=8)
self.assertAlmostEqual(surf.area(), desired_area, places=8)
self.assertLess(np.abs(prob.objective()), 1.0e-15)
Optimize the minor radius and elongation of an axisymmetric torus to
obtain a desired volume and area.
"""
desired_volume = 0.6
desired_area = 8.0
# Start with a default surface, which is axisymmetric with major
# radius 1 and minor radius 0.1.
surf = SurfaceRZFourier()
# Parameters are all non-fixed by default, meaning they will be
# optimized. You can choose to exclude any subset of the variables
# from the space of independent variables by setting their 'fixed'
# property to True.
surf.set_fixed('rc(0,0)')
# Each target function is then equipped with a shift and weight, to
# become a term in a least-squares objective function
term1 = (surf.volume, desired_volume, 1)
term2 = (surf.area, desired_area, 1)
# A list of terms are combined to form a nonlinear-least-squares
# problem.
prob = LeastSquaresProblem([term1, term2])
# Solve the minimization problem:
least_squares_serial_solve(prob)
print("At the optimum,")
print(" rc(m=1,n=0) = ", surf.get_rc(1, 0))
