fix some tests

pina/problem/zoo/__init__.py

@@ -0,0 +1,5 @@
+__all__ = [
+    'Poisson2DSquareProblem'
+]
+
+from .poisson_2d_square import Poisson2DSquareProblem

pina/problem/zoo/poisson_2d_square.py

@@ -0,0 +1,44 @@
+""" Definition of the Poisson problem on a square domain."""
+
+from pina.problem import SpatialProblem
+from pina.operators import laplacian
+from pina import LabelTensor, Condition
+from pina.domain import CartesianDomain
+from pina.equation.equation import Equation
+from pina.equation.equation_factory import FixedValue
+import torch
+
+def laplace_equation(input_, output_):
+    force_term = (torch.sin(input_.extract(['x']) * torch.pi) *
+                  torch.sin(input_.extract(['y']) * torch.pi))
+    delta_u = laplacian(output_.extract(['u']), input_)
+    return delta_u - force_term
+
+
+my_laplace = Equation(laplace_equation)
+
+
+class Poisson2DSquareProblem(SpatialProblem):
+    output_variables = ['u']
+    spatial_domain = CartesianDomain({'x': [0, 1], 'y': [0, 1]})
+
+    domains = {
+        'D': CartesianDomain({'x': [0, 1], 'y': [0, 1]}),
+        'g1': CartesianDomain({'x': [0, 1], 'y': 1}),
+        'g2': CartesianDomain({'x': [0, 1], 'y': 0}),
+        'g3': CartesianDomain({'x': 1, 'y': [0, 1]}),
+        'g4': CartesianDomain({'x': 0, 'y': [0, 1]}),
+    }
+
+    conditions = {
+        'nil_g1': Condition(domain='D', equation=FixedValue(0.0)),
+        'nil_g2': Condition(domain='D', equation=FixedValue(0.0)),
+        'nil_g3': Condition(domain='D', equation=FixedValue(0.0)),
+        'nil_g4': Condition(domain='D', equation=FixedValue(0.0)),
+        'laplace_D': Condition(domain='D', equation=my_laplace),
+    }
+
+    def poisson_sol(self, pts):
+        return -(torch.sin(pts.extract(['x']) * torch.pi) *
+                 torch.sin(pts.extract(['y']) * torch.pi))
+