[BUG] sigmoid_slope broken when was an array for finite faults

Author: Leguark

gempy_engine/modules/activator/activator_interface.py

@@ -12,7 +12,9 @@ def activate_formation_block(exported_fields: ExportedFields, ids: np.ndarray,
     Z_x: np.ndarray = exported_fields.scalar_field_everywhere
     scalar_value_at_sp: np.ndarray = exported_fields.scalar_field_at_surface_points
 
-    if LEGACY := True and sigmoid_slope > 0: # * Here we branch to the experimental activation function with hard sigmoid
+    sigmoid_slope_negative = isinstance(sigmoid_slope, float) and sigmoid_slope < 0 # * sigmoid_slope can be array for finite faultskA
+    
+    if LEGACY := True and not sigmoid_slope_negative: # * Here we branch to the experimental activation function with hard sigmoid
         sigm = activate_formation_block_from_args(Z_x, ids, scalar_value_at_sp, sigmoid_slope)
     else:
         from .torch_activation import activate_formation_block_from_args_hard_sigmoid