def test_l2_h1_1():
eps = 1e-12
eps_low = 1e-10
func = lambda x: sin(x)
mesh1 = Mesh1D((0, pi), (20, ))
mesh2 = Mesh1D((0, pi / 2, pi), (20, 20))
mesh3 = Mesh1D((0, pi / 2), (20, ))
f = Function(func, mesh1)
g = Function(func, mesh2)
h = Function(func, mesh3)
assert abs(f.l2_norm(method="Fekete") - sqrt(pi / 2)) < eps
assert abs(g.l2_norm(method="Fekete") - sqrt(pi / 2)) < eps
assert abs(h.l2_norm(method="Fekete") - sqrt(pi / 4)) < eps
assert abs(f.l2_norm(method="FE") - sqrt(pi / 2)) < eps
assert abs(g.l2_norm(method="FE") - sqrt(pi / 2)) < eps
assert abs(h.l2_norm(method="FE") - sqrt(pi / 4)) < eps
assert abs(f.h1_norm() - sqrt(pi)) < eps_low
assert abs(g.h1_norm() - sqrt(pi)) < eps_low
assert abs(h.h1_norm() - sqrt(pi / 2)) < eps_low
func = lambda x: cos(x)
mesh1 = Mesh1D((0, pi / 4, pi / 2, 3 * pi / 4, pi), (20, 20, 20, 20))
f = Function(func, mesh1)
assert abs(f.l2_norm(method="Fekete") - sqrt(pi / 2)) < eps
assert abs(f.l2_norm(method="FE") - sqrt(pi / 2)) < eps
assert abs(f.h1_norm() - sqrt(pi)) < eps
def test3():
eps = 1e-12
func = lambda x: x**2
f = Function(func, Mesh1D((-5, -4, 3, 10), (1, 5, 1)))
for x in [-4, -3, -2, -1, 0, 0.01, 1e-5, 1, 2, 3]:
assert abs(f(x) - func(x)) < eps
func = lambda x: x**3
f = Function(func, Mesh1D((-5, -4, 3, 10), (1, 5, 1)))
for x in [-4, -3, -2, -1, 0, 0.01, 1e-5, 1, 2, 3]:
assert abs(f(x) - func(x)) < eps
func = lambda x: x**4
f = Function(func, Mesh1D((-5, -4, 3, 10), (1, 5, 1)))
for x in [-4, -3, -2, -1, 0, 0.01, 1e-5, 1, 2, 3]:
assert abs(f(x) - func(x)) < eps
func = lambda x: x**5
f = Function(func, Mesh1D((-5, -4, 3, 10), (1, 5, 1)))
for x in [-4, -3, -2, -1, 0, 0.01, 1e-5, 1, 2, 3]:
assert abs(f(x) - func(x)) < eps
func = lambda x: x**6
f = Function(func, Mesh1D((-5, -4, 3, 10), (1, 5, 1)))
x = -1
assert abs(f(x) - func(x)) > 61.9
x = 0
assert abs(f(x) - func(x)) > 61.9
x = 1
assert abs(f(x) - func(x)) > 61.6
x = 2
assert abs(f(x) - func(x)) > 28.9
def test4():
eps = 1e-12
func = lambda x: x**2
orig_mesh = Mesh1D((-5, -4, 3, 10), (1, 5, 1))
mesh1 = Mesh1D((-5, -4, 3, 10), (1, 1, 1))
f = Function(func, orig_mesh)
g = f.project_onto(mesh1)
h = Function(func, mesh1)
assert g == Function(func, mesh1)
assert h == h.project_onto(orig_mesh)
def test_l2_h1_proj6():
"""
Tests exact projections.
Slightly more complicated example.
"""
f_exact = lambda x: sin(x)*exp(x)
f_exact_l2 = lambda x: -e*cos(1)/4 + e*sin(1)/4 + exp(-1)*sin(1)/4 + 3*x*(e*sin(1)/2 - exp(-1)*sin(1)/2 - cos(1)*exp(-1))/2 + cos(1)*exp(-1)/4
pts = [-1, -0.5, 0, 0.5, 1]
orders = [20]*(len(pts)-1)
m = Mesh1D(pts, orders)
f = Function(f_exact, m)
pts = [-1, 1]
orders = [1]*(len(pts)-1)
m = Mesh1D(pts, orders)
f_proj_l2 = Function(f_exact_l2, m)
assert (f.project_onto(m, proj_type="L2") - f_proj_l2).l2_norm() < 0.03
def test_l2_h1_2():
eps = 1e-9
func = lambda x: log(x)
mesh1 = Mesh1D((1, 1.5, 2, 2.5, e), (20, 20, 20, 20))
f = Function(func, mesh1)
l2_norm_exact = sqrt(e - 2)
h1_norm_exact = sqrt(e - 1 - exp(-1))
assert abs(f.l2_norm(method="Fekete") - l2_norm_exact) < eps
assert abs(f.l2_norm(method="FE") - l2_norm_exact) < eps
assert abs(f.h1_norm() - h1_norm_exact) < eps
def test5():
eps = 1e-12
func = lambda x: x**2
mesh1 = Mesh1D((-5, -4, 3, 10), (2, 5, 2))
mesh2 = Mesh1D((-5, -4, 3, 10), (2, 2, 2))
mesh3 = Mesh1D((-5, -4, 3, 10), (2, 2, 1))
mesh4 = Mesh1D((-5, 10), (2, ))
mesh5 = Mesh1D((-5, 10), (3, ))
mesh6 = Mesh1D((-5, 10), (1, ))
f = Function(func, mesh1)
g = Function(func, mesh2)
h = Function(func, mesh3)
l = Function(func, mesh4)
assert f == g
assert g == f
assert f == l
assert g == l
assert f != h
assert h != f
assert g != h
assert h != g
assert f == Function(lambda x: x**2, mesh1)
assert f != Function(lambda x: x**3, mesh1)
assert f == Function(lambda x: x**2, mesh2)
assert f == Function(lambda x: x**2, mesh4)
assert f == Function(lambda x: x**2, mesh5)
assert f != Function(lambda x: x**2, mesh6)
def test_l2_h1_proj5():
"""
Tests exact projections.
The exact results were generated using:
from sympy import sin, cos, integrate, var, pi, exp, log, E, S
var("x")
f = exp(x)
S(1)/2 * integrate(f, (x, -1, 1)) + S(3)/2*x*integrate(x*f, (x, -1, 1))
"""
f_exact = lambda x: exp(x)
f_exact_l2 = lambda x: e / 2 - exp(-1) / 2 + 3 * x * exp(-1)
# TODO: The constant term here has to be checked:
f_exact_h1 = lambda x: +3 * e / 8 + 3 * exp(-1) / 8 + 3 * x * (e + exp(-1)
) / 8
pts = [-1, -0.5, 0, 0.5, 1]
orders = [20] * (len(pts) - 1)
m = Mesh1D(pts, orders)
f = Function(f_exact, m)
pts = [-1, 1]
orders = [1] * (len(pts) - 1)
m = Mesh1D(pts, orders)
f_proj_l2_exact = Function(f_exact_l2, m)
f_proj_l2 = f.project_onto(m, proj_type="L2")
f_proj_h1_exact = Function(f_exact_h1, m)
f_proj_h1 = f.project_onto(m, proj_type="H1")
eps_l2 = 1e-3
eps_h1 = 0.03
assert (f_proj_l2 - f_proj_l2_exact).l2_norm() < eps_l2
assert (f_proj_h1 - f_proj_h1_exact).l2_norm() < eps_h1
# Make sure that if we exchange the L2 and H1 solutions, then the test
# fails:
assert (f_proj_l2 - f_proj_h1_exact).l2_norm() > max(eps_l2, eps_h1)
assert (f_proj_h1 - f_proj_l2_exact).l2_norm() > max(eps_l2, eps_h1)
def test2():
eps = 1e-12
func = lambda x: x**2
f = Function(func, Mesh1D((-5, -4, 3, 10), (2, 5, 2)))
for x in [
-5, -4.5, -4, -3, -2, -1, 0, 0.01, 1e-5, 1, 2, 3, 4, 5, 6, 7, 10
]:
assert abs(f(x) - func(x)) < eps
f = Function(func, Mesh1D((-5, -4, 3, 10), (1, 5, 2)))
for x in [-5, -4, -3, -2, -1, 0, 0.01, 1e-5, 1, 2, 3, 4, 5, 6, 7, 10]:
assert abs(f(x) - func(x)) < eps
x = -4.9
assert abs(f(x) - func(x)) > 0.08
x = -4.5
assert abs(f(x) - func(x)) > 0.24
f = Function(func, Mesh1D((-5, -4, 3, 10), (1, 5, 1)))
for x in [-5, -4, -3, -2, -1, 0, 0.01, 1e-5, 1, 2, 3, 10]:
assert abs(f(x) - func(x)) < eps
x = -4.9
assert abs(f(x) - func(x)) > 0.08
x = -4.5
assert abs(f(x) - func(x)) > 0.24
x = 4
assert abs(f(x) - func(x)) > 5.9
x = 5
assert abs(f(x) - func(x)) > 9.9
x = 6
assert abs(f(x) - func(x)) > 11.9
x = 7
assert abs(f(x) - func(x)) > 11.9
x = 8
assert abs(f(x) - func(x)) > 9.9
x = 9
assert abs(f(x) - func(x)) > 5.9
def test_l2_h1_proj4():
"""
Tests conversion to FE basis.
"""
pts = arange(0, 2 * pi, 0.4)
orders = [2] * (len(pts) - 1)
m = Mesh1D(pts, orders)
f = Function(lambda x: sin(x), m)
assert f.project_onto(m, proj_type="Fekete") == f
assert f.project_onto(m, proj_type="L2") == f
assert f.project_onto(m, proj_type="H1") == f
orders = [3] * (len(pts) - 1)
m = Mesh1D(pts, orders)
assert f.project_onto(m, proj_type="Fekete") == f
assert f.project_onto(m, proj_type="L2") == f
assert f.project_onto(m, proj_type="H1") == f
orders = [4] * (len(pts) - 1)
m = Mesh1D(pts, orders)
assert f.project_onto(m, proj_type="Fekete") == f
assert f.project_onto(m, proj_type="L2") == f
assert f.project_onto(m, proj_type="H1") == f
pts = arange(0, 2 * pi, 3)
orders = [2] * (len(pts) - 1)
m = Mesh1D(pts, orders)
pts = array(list(arange(0, pts[-1], 0.1)) + [pts[-1]])
orders = [6] * (len(pts) - 1)
f_exact = Function(lambda x: sin(x), Mesh1D(pts, orders))
sol_l2 = f_exact.project_onto(m, proj_type="L2")
sol_h1 = f_exact.project_onto(m, proj_type="H1")
assert (sol_l2 - f_exact).l2_norm() < 0.07
assert (sol_h1 - f_exact).l2_norm() < 0.07
def test8():
eps = 1e-12
func = lambda x: x**2
mesh1 = Mesh1D((-5, -4, 3, 10), (2, 5, 2))
mesh2 = Mesh1D((-5, -4, 3, 10), (2, 2, 2))
mesh3 = Mesh1D((-5, -4, 3, 10), (2, 2, 1))
mesh4 = Mesh1D((-5, 10), (2, ))
mesh5 = Mesh1D((-5, 10), (3, ))
mesh6 = Mesh1D((-5, 10), (1, ))
f = Function(func, mesh1)
g = Function(func, mesh2)
h = Function(func, mesh3)
l = Function(func, mesh4)
zero = Function(lambda x: 0., Mesh1D((-5, 10), (1, )))
assert zero.l2_norm() < eps
assert Function(lambda x: 0., mesh1) == zero
assert Function(lambda x: 0., mesh2) == zero
assert Function(lambda x: 0., mesh3) == zero
assert Function(lambda x: 0., mesh4) == zero
assert Function(lambda x: 0., mesh5) == zero
assert Function(lambda x: 0., mesh6) == zero
assert f - g == zero
assert (f - g).l2_norm() < eps
assert g - f == zero
assert (g - f).l2_norm() < eps
assert f - l == zero
assert (f - l).l2_norm() < eps
assert g - l == zero
assert (g - l).l2_norm() < eps
assert f - h != zero
assert (f - h).l2_norm() > eps
assert h - f != zero
assert (h - f).l2_norm() > eps
assert g - h != zero
assert (g - h).l2_norm() > eps
assert h - g != zero
assert (h - g).l2_norm() > eps
assert f - Function(lambda x: x**2, mesh1) == zero
assert f - Function(lambda x: x**3, mesh1) != zero
assert f - Function(lambda x: x**2, mesh2) == zero
assert f - Function(lambda x: x**2, mesh4) == zero
assert f - Function(lambda x: x**2, mesh5) == zero
assert f - Function(lambda x: x**2, mesh6) != zero
def test_l2_h1_proj3():
"""
Tests conversion to FE basis.
"""
pts = arange(0, 2 * pi, 0.1)
orders = [2] * (len(pts) - 1)
m = Mesh(pts, orders)
f = Function(lambda x: sin(x), Mesh1D(pts, orders))
n_dof = m.assign_dofs()
A = CSCMatrix(n_dof)
rhs = AVector(n_dof)
assemble_projection_matrix_rhs(m, A, rhs, f, projection_type="L2")
x = solve(A.to_scipy_csc().todense(), rhs.to_numpy())
sol_l2 = FESolution(m, x).to_discrete_function()
A = CSCMatrix(n_dof)
assemble_projection_matrix_rhs(m, A, rhs, f, projection_type="H1")
x = solve(A.to_scipy_csc().todense(), rhs.to_numpy())
sol_h1 = FESolution(m, x).to_discrete_function()
assert sol_l2 == f
assert sol_h1 == f
def test_l2_h1_proj2():
"""
Tests the correctness of the projections.
"""
pts = arange(0, 2 * pi, 3)
orders = [4] * (len(pts) - 1)
m = Mesh(pts, orders)
pts = array(list(arange(0, pts[-1], 0.1)) + [pts[-1]])
orders = [6] * (len(pts) - 1)
f_exact = Function(lambda x: sin(x), Mesh1D(pts, orders))
n_dof = m.assign_dofs()
A = CSCMatrix(n_dof)
rhs = AVector(n_dof)
assemble_projection_matrix_rhs(m, A, rhs, f_sin, projection_type="L2")
x = solve(A.to_scipy_csc().todense(), rhs.to_numpy())
sol_l2 = FESolution(m, x).to_discrete_function()
A = CSCMatrix(n_dof)
assemble_projection_matrix_rhs(m, A, rhs, f_sin, projection_type="H1")
x = solve(A.to_scipy_csc().todense(), rhs.to_numpy())
sol_h1 = FESolution(m, x).to_discrete_function()
assert (sol_l2 - f_exact).l2_norm() < 0.002
assert (sol_h1 - f_exact).l2_norm() < 0.002
def test6():
mesh1 = Mesh1D((-5, -4, 3, 10), (2, 5, 2))
mesh2 = Mesh1D((-5, -4, 3, 10), (2, 2, 2))
mesh3 = Mesh1D((-5, -4, 3, 10), (2, 2, 1))
mesh4 = Mesh1D((-5, 10), (2, ))
mesh5 = Mesh1D((-5, 10), (3, ))
mesh6 = Mesh1D((-5, 10), (1, ))
mesh7 = Mesh1D((-5, 10), (1, ))
mesh8 = Mesh1D((-5, 0, 10), (1, 4))
assert mesh1 == mesh1
assert not (mesh1 != mesh1)
assert mesh1 != mesh2
assert mesh1 != mesh3
assert mesh1 != mesh4
assert mesh1 != mesh5
assert mesh1 != mesh6
assert mesh6 == mesh7
assert mesh1.union(mesh1) == mesh1
assert mesh1.union(mesh2) == mesh1
assert mesh2.union(mesh1) == mesh1
assert mesh1.union(mesh3) == mesh1
assert mesh3.union(mesh1) == mesh1
assert mesh1.union(mesh4) == mesh1
assert mesh4.union(mesh1) == mesh1
assert mesh1.union(mesh5) == Mesh1D((-5, -4, 3, 10), (3, 5, 3))
assert mesh5.union(mesh1) == Mesh1D((-5, -4, 3, 10), (3, 5, 3))
assert mesh1.union(mesh6) == mesh1
assert mesh6.union(mesh1) == mesh1
assert mesh1.union(mesh8) == Mesh1D((-5, -4, 0, 3, 10), (2, 5, 5, 4))
assert mesh8.union(mesh1) == Mesh1D((-5, -4, 0, 3, 10), (2, 5, 5, 4))
def test_power():
eps = 1e-12
func = lambda x: x
mesh1 = Mesh1D((0, 1), (1, ))
mesh2 = Mesh1D((0, 1), (2, ))
mesh3 = Mesh1D((0, 1), (3, ))
f = Function(func, mesh1)
assert abs(f.l2_norm() - sqrt(1. / 3)) < eps
assert f**2 != Function(lambda x: x**2, mesh1)
assert f**2 == Function(lambda x: x**2, mesh2)
assert f**2 == Function(lambda x: x**2, mesh3)
func = lambda x: x
mesh1 = Mesh1D((5, 6), (1, ))
mesh2 = Mesh1D((5, 6), (2, ))
mesh3 = Mesh1D((5, 6), (3, ))
f = Function(func, mesh1)
assert f**2 != Function(lambda x: x**2, mesh1)
assert f**2 == Function(lambda x: x**2, mesh2)
assert f**2 == Function(lambda x: x**2, mesh3)
func = lambda x: x**3 + x
mesh1 = Mesh1D((5, 6), (3, ))
mesh2 = Mesh1D((5, 6), (5, ))
mesh3 = Mesh1D((5, 6), (6, ))
mesh4 = Mesh1D((5, 6), (9, ))
f = Function(func, mesh1)
assert f**2 != Function(lambda x: x**6 + 2 * x**4 + x**2, mesh1)
assert f**2 != Function(lambda x: x**6 + 2 * x**4 + x**2, mesh2)
assert f**2 == Function(lambda x: x**6 + 2 * x**4 + x**2, mesh3)
assert f**3 == Function(lambda x: x**3 + 3 * x**5 + 3 * x**7 + x**9, mesh4)
func = lambda x: x**3 + x
mesh1 = Mesh1D((5, 5.1, 6), (3, 3))
mesh2 = Mesh1D((5, 5.1, 6), (5, 5))
mesh3 = Mesh1D((5, 5.1, 6), (6, 6))
mesh4 = Mesh1D((5, 5.1, 6), (9, 9))
mesh5 = Mesh1D((5, 5.1, 6), (9, 7))
mesh6 = Mesh1D((5, 5.1, 6), (6, 5))
mesh7 = Mesh1D((5, 6), (6, ))
mesh8 = Mesh1D((5, 6), (9, ))
f = Function(func, mesh1)
assert f**2 != Function(lambda x: x**6 + 2 * x**4 + x**2, mesh1)
assert f**2 != Function(lambda x: x**6 + 2 * x**4 + x**2, mesh2)
assert f**2 != Function(lambda x: x**6 + 2 * x**4 + x**2, mesh6)
assert f**2 == Function(lambda x: x**6 + 2 * x**4 + x**2, mesh3)
assert f**3 == Function(lambda x: x**3 + 3 * x**5 + 3 * x**7 + x**9, mesh4)
assert f**3 != Function(lambda x: x**3 + 3 * x**5 + 3 * x**7 + x**9, mesh5)
assert f**2 == Function(lambda x: x**6 + 2 * x**4 + x**2, mesh7)
assert f**3 == Function(lambda x: x**3 + 3 * x**5 + 3 * x**7 + x**9, mesh8)
def test1():
m = Mesh1D((-5, -4, 3, 10), (1, 5, 1))
def adapt_mesh(mesh, eigs, l=0, Z=1, adapt_type="hp", eqn_type="R"):
"""
Adapts the mesh using the adaptivity type 'adapt_type'.
Returns a new instance of the H1D mesh.
adapt_type .... one of: h, hp, p, uniform-p, romanowski
"""
if adapt_type == "romanowski":
m = refine_mesh_romanowski(mesh, eigs)
pts, orders = m.get_mesh_data()
return Mesh(pts, orders)
elif adapt_type == "uniform-p":
pts, orders = mesh.get_mesh_data()
orders = array(orders) + 1
return Mesh(pts, orders)
elif adapt_type in ["h", "p", "hp"]:
NORM = 1 # 1 ... H1; 0 ... L2;
THRESHOLD = 0.7
mesh_ref = mesh.reference_refinement()
print "Fine mesh created (%d DOF)." % mesh_ref.get_n_dof()
N_dof, energies, eigs_ref = solve_schroedinger(mesh_ref,
l=l,
Z=Z,
eqn_type=eqn_type,
eig_num=len(eigs))
flip_vectors(mesh, eigs, mesh_ref, eigs_ref)
print " Done."
sols = []
sols_ref = []
print "Normalizing solutions..."
for i in range(len(eigs)):
e = (eigs[i]).copy()
coarse_h1_norm = FESolution(mesh, e).h1_norm()
e /= coarse_h1_norm
sols.append(e)
e = (eigs_ref[i]).copy()
reference_h1_norm = FESolution(mesh_ref, e).h1_norm()
e /= reference_h1_norm
sols_ref.append(e)
#print "H1 norms:"
#print "coarse (%d):" % i, coarse_h1_norm
#print "reference (%d):" % i, reference_h1_norm
print " Done."
meshes = []
mesh_orig = mesh.copy()
mesh_orig.assign_dofs()
errors = []
for sol, sol_ref in zip(sols, sols_ref):
mesh = mesh_orig.copy()
mesh.assign_dofs()
mesh_ref = mesh.reference_refinement()
mesh_ref.assign_dofs()
mesh.copy_vector_to_mesh(sol, 0)
mesh_ref.copy_vector_to_mesh(sol_ref, 0)
err_est_total, err_est_array = calc_error_estimate(
NORM, mesh, mesh_ref)
ref_sol_norm = calc_solution_norm(NORM, mesh_ref)
err_est_rel = err_est_total / ref_sol_norm
print "Relative error (est) = %g %%\n" % (100. * err_est_rel)
errors.append(err_est_rel)
# TODO: adapt using all the vectors:
# 0 ... hp, 1 ... h, 2 ... p
if adapt_type == "hp":
ADAPT_TYPE = 0
elif adapt_type == "h":
ADAPT_TYPE = 1
elif adapt_type == "p":
ADAPT_TYPE = 2
else:
raise ValueError("Unkown adapt_type")
adapt(NORM, ADAPT_TYPE, THRESHOLD, err_est_array, mesh, mesh_ref)
meshes.append(mesh)
pts, orders = mesh_orig.get_mesh_data()
mesh = Mesh1D(pts, orders)
for m in meshes:
pts, orders = m.get_mesh_data()
m = Mesh1D(pts, orders)
mesh = mesh.union(m)
pts, orders = mesh.get_mesh_data()
mesh = Mesh(pts, orders)
return mesh
else:
raise ValueError("Unknown adapt_type")
def test7():
mesh1 = Mesh1D((-5, -4, 3, 10), (2, 5, 2))
mesh2 = Mesh1D((-5, -4, 3, 10), (2, 2, 2))
mesh3 = Mesh1D((-5, -4, 3, 10), (2, 2, 1))
mesh4 = Mesh1D((-5, 10), (2, ))
mesh5 = Mesh1D((-5, 10), (3, ))
mesh6 = Mesh1D((-5, 10), (1, ))
mesh8 = Mesh1D((-5, 0, 10), (1, 4))
assert mesh1.restrict_to_interval(-5, 10) == mesh1
assert mesh1.restrict_to_interval(-4.5, 10) == Mesh1D((-4.5, -4, 3, 10),
(2, 5, 2))
assert mesh1.restrict_to_interval(-4, 10) != mesh1
assert mesh1.restrict_to_interval(-4, 10) == Mesh1D((-4, 3, 10), (5, 2))
assert mesh1.restrict_to_interval(-3.5, 10) == Mesh1D((-3.5, 3, 10),
(5, 2))
assert mesh1.restrict_to_interval(3, 10) == Mesh1D((3, 10), (2, ))
assert mesh1.restrict_to_interval(3.5, 10) == Mesh1D((3.5, 10), (2, ))
assert mesh2.restrict_to_interval(-5, 10) == mesh2
assert mesh2.restrict_to_interval(-4.5, 10) == Mesh1D((-4.5, -4, 3, 10),
(2, 2, 2))
assert mesh2.restrict_to_interval(-4, 10) != mesh2
assert mesh2.restrict_to_interval(-4, 10) == Mesh1D((-4, 3, 10), (2, 2))
assert mesh2.restrict_to_interval(-3.5, 10) == Mesh1D((-3.5, 3, 10),
(2, 2))
assert mesh2.restrict_to_interval(3, 10) == Mesh1D((3, 10), (2, ))
assert mesh2.restrict_to_interval(3.5, 10) == Mesh1D((3.5, 10), (2, ))
assert mesh3.restrict_to_interval(-5, 10) == mesh3
assert mesh3.restrict_to_interval(-4.5, 10) == Mesh1D((-4.5, -4, 3, 10),
(2, 2, 1))
assert mesh3.restrict_to_interval(-4, 10) != mesh3
assert mesh3.restrict_to_interval(-4, 10) == Mesh1D((-4, 3, 10), (2, 1))
assert mesh3.restrict_to_interval(-3.5, 10) == Mesh1D((-3.5, 3, 10),
(2, 1))
assert mesh3.restrict_to_interval(3, 10) == Mesh1D((3, 10), (1, ))
assert mesh3.restrict_to_interval(3.5, 10) == Mesh1D((3.5, 10), (1, ))
