Enhancing Equations

- add init file
- add docs
- fixing bug System of equation, replace torch.stack with torch.hstack
- add tests

tests/test_equations/test_equation.py

@@ -0,0 +1,43 @@
+from pina.equation import Equation
+from pina.operators import grad, nabla
+from pina import LabelTensor
+import torch
+import pytest
+
+def eq1(input_, output_):
+    u_grad = grad(output_, input_)
+    u1_xx = grad(u_grad, input_, components=['du1dx'], d=['x'])
+    u2_xy = grad(u_grad, input_, components=['du2dx'], d=['y'])
+    return torch.hstack([u1_xx , u2_xy])  
+
+def eq2(input_, output_):
+    force_term = (torch.sin(input_.extract(['x'])*torch.pi) *
+                    torch.sin(input_.extract(['y'])*torch.pi))
+    nabla_u = nabla(output_.extract(['u1']), input_)
+    return nabla_u - force_term
+
+def foo():
+    pass
+
+def test_constructor():
+    Equation(eq1)
+    Equation(eq2)
+    with pytest.raises(ValueError):
+        Equation([1, 2, 4])
+    with pytest.raises(ValueError):
+        Equation(foo())
+
+def test_residual():
+    eq_1 = Equation(eq1)
+    eq_2 = Equation(eq2)
+
+    pts = LabelTensor(torch.rand(10, 2), labels=['x', 'y'])
+    pts.requires_grad = True
+    u = torch.pow(pts, 2)
+    u.labels = ['u1', 'u2']
+
+    eq_1_res = eq_1.residual(pts, u)
+    eq_2_res = eq_2.residual(pts, u)
+
+    assert eq_1_res.shape == torch.Size([10, 2])
+    assert eq_2_res.shape == torch.Size([10, 1])

tests/test_equations/test_systemequation.py

@@ -0,0 +1,47 @@
+from pina.equation import SystemEquation
+from pina.operators import grad, nabla
+from pina import LabelTensor
+import torch
+import pytest
+
+def eq1(input_, output_):
+    u_grad = grad(output_, input_)
+    u1_xx = grad(u_grad, input_, components=['du1dx'], d=['x'])
+    u2_xy = grad(u_grad, input_, components=['du2dx'], d=['y'])
+    return torch.hstack([u1_xx , u2_xy])  
+
+def eq2(input_, output_):
+    force_term = (torch.sin(input_.extract(['x'])*torch.pi) *
+                    torch.sin(input_.extract(['y'])*torch.pi))
+    nabla_u = nabla(output_.extract(['u1']), input_)
+    return nabla_u - force_term
+
+def foo():
+    pass
+
+def test_constructor():
+    SystemEquation([eq1, eq2])
+    SystemEquation([eq1, eq2], reduction='sum')
+    with pytest.raises(NotImplementedError):
+        SystemEquation([eq1, eq2], reduction='foo')
+    with pytest.raises(ValueError):
+        SystemEquation(foo)
+
+def test_residual():
+
+    pts = LabelTensor(torch.rand(10, 2), labels=['x', 'y'])
+    pts.requires_grad = True
+    u = torch.pow(pts, 2)
+    u.labels = ['u1', 'u2']
+
+    eq_1 = SystemEquation([eq1, eq2])
+    res = eq_1.residual(pts, u)
+    assert res.shape == torch.Size([10])
+
+    eq_1 = SystemEquation([eq1, eq2], reduction='sum')
+    res = eq_1.residual(pts, u)
+    assert res.shape == torch.Size([10])
+
+    eq_1 = SystemEquation([eq1, eq2], reduction='none')
+    res = eq_1.residual(pts, u)
+    assert res.shape == torch.Size([10, 3])