docs: record that edge-zeroing is deliberately scoped to the positive-only solver

autoarray/config/general.yaml

@@ -3,7 +3,7 @@ psf:
 inversion:
   check_reconstruction: true          # If True, the inversion's reconstruction is checked to ensure the solution of a meshs's mapper is not an invalid solution where the values are all the same.
   use_positive_only_solver: true      # If True, inversion's use a positive-only linear algebra solver by default, which is slower but prevents unphysical negative values in the reconstructed solutuion.
-  use_edge_zeroed_pixels : true       # If True, the edge pixels of a pixelization are set to zero, which prevents unphysical values in the reconstructed solution at the edge of the pixelization.
+  use_edge_zeroed_pixels : true       # If True, the edge pixels of a pixelization are set to zero, which prevents unphysical values in the reconstructed solution at the edge of the pixelization. NOTE: this is applied ONLY when use_positive_only_solver is True -- with the positive-negative solver it has no effect. That scoping is deliberate, not an oversight.
   no_regularization_add_to_curvature_diag_value : 1.0e-3 # The default value added to the curvature matrix's diagonal when regularization is not applied to a linear object, which prevents inversion's failing due to the matrix being singular.
   use_border_relocator: false          # If True, by default a pixelization's border is used to relocate all pixels outside its border to the border.
   nnls_jacobi_preconditioning: true   # If True (default), the curvature matrix passed to jaxnnls.solve_nnls_primal is Jacobi-preconditioned (D Q D y = D q, x = D y). Fixes NaN backward-pass gradients on ill-conditioned Q and roughly halves forward solve time. Set False to restore the raw unpreconditioned solve.

autoarray/inversion/inversion/abstract.py

@@ -509,6 +509,10 @@ def reconstruction(self) -> np.ndarray:
 
         if self.settings.use_positive_only_solver:
 
+            # `use_edge_zeroed_pixels` is deliberately nested here rather than checked alongside
+            # `use_positive_only_solver`: edge-zeroing is scoped to the positive-only solver, and the
+            # positive-negative branch below solves the full system regardless of its value. This is
+            # intended, not an oversight -- do not "fix" it by hoisting the check out of this branch.
             if self.settings.use_edge_zeroed_pixels and self.has(cls=Mapper):
 
                 # Use advanced indexing to select rows/columns

autoarray/settings.py

@@ -169,6 +169,17 @@ def use_positive_only_solver(self):
 
     @property
     def use_edge_zeroed_pixels(self):
+        """
+        Whether a mesh's edge pixels are excluded from the inversion and fixed to zero.
+
+        This is consulted **only when `use_positive_only_solver` is `True`**. Under the
+        positive-negative solver the full system is solved and this setting has no effect, so the two
+        are not independent switches despite reading that way in `config/general.yaml`.
+
+        That scoping is deliberate. It is called out here because the nesting is not visible from the
+        config, and has been mistaken for a bug (a setting "silently ignored") by someone reading the
+        control flow in `AbstractInversion.reconstruction` without it.
+        """
         if self._use_edge_zeroed_pixels is None:
             return conf.instance["general"]["inversion"]["use_edge_zeroed_pixels"]