fix bugs for helmholtz and advection (#686)

pina/equation/equation_factory.py

@@ -239,19 +239,19 @@ class Advection(Equation):  # pylint: disable=R0903
                 )
 
             # Ensure consistency of c length
-            if len(self.c) != (len(input_lbl) - 1) and len(self.c) > 1:
+            if self.c.shape[-1] != len(input_lbl) - 1 and self.c.shape[-1] > 1:
                 raise ValueError(
                     "If 'c' is passed as a list, its length must be equal to "
                     "the number of spatial dimensions."
                 )
 
             # Repeat c to ensure consistent shape for advection
-            self.c = self.c.repeat(output_.shape[0], 1)
-            if self.c.shape[1] != (len(input_lbl) - 1):
-                self.c = self.c.repeat(1, len(input_lbl) - 1)
+            c = self.c.repeat(output_.shape[0], 1)
+            if c.shape[1] != (len(input_lbl) - 1):
+                c = c.repeat(1, len(input_lbl) - 1)
 
             # Add a dimension to c for the following operations
-            self.c = self.c.unsqueeze(-1)
+            c = c.unsqueeze(-1)
 
             # Compute the time derivative and the spatial gradient
             time_der = grad(output_, input_, components=None, d="t")
@@ -262,7 +262,7 @@ class Advection(Equation):  # pylint: disable=R0903
             tmp = tmp.transpose(-1, -2)
 
             # Compute advection term
-            adv = (tmp * self.c).sum(dim=tmp.tensor.ndim - 2)
+            adv = (tmp * c).sum(dim=tmp.tensor.ndim - 2)
 
             return time_der + adv
 

pina/problem/zoo/helmholtz.py

@@ -48,11 +48,10 @@ class HelmholtzProblem(SpatialProblem):
         :type alpha: float | int
         """
         super().__init__()
-
-        self.alpha = alpha
         check_consistency(alpha, (int, float))
+        self.alpha = alpha
 
-        def forcing_term(self, input_):
+        def forcing_term(input_):
             """
             Implementation of the forcing term.
             """