From 7578cefdadd619b505f2b9ad35e5a5067a51d9e6 Mon Sep 17 00:00:00 2001
From: Dieter Werthmuller <mail@werthmuller.org>
Date: Thu, 2 Jan 2025 17:16:29 +0100
Subject: [PATCH] Bugfix, closes #348

---
 CHANGELOG.rst        | 11 +++++++----
 emg3d/fields.py      |  6 ++++--
 tests/test_fields.py | 24 +++++++++++++++++-------
 3 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index afdab7fe..b104b1a9 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -6,12 +6,15 @@ Changelog
 """"""""""
 
 
-latest
-------
+v1.8.5 : Bugfix and pyproject
+-----------------------------
 
-- Maintenance:
+- Bugfix and maintenance:
 
-  - Changed from ``setup.py`` to ``pyproject.toml``.
+  - Fix bug in Dipole/Wire sources when coordinates are mixed increasing and
+    decreasing over several cells
+    [#348](https://github.com/emsig/emg3d/issues/348).
+  - Changed build backend from ``setup.py`` to ``pyproject.toml``.
 
 
 v1.8.4 : NumPy v2
diff --git a/emg3d/fields.py b/emg3d/fields.py
index ceb15491..3572955c 100644
--- a/emg3d/fields.py
+++ b/emg3d/fields.py
@@ -898,7 +898,7 @@ def min_max_ind(vector, i):
                 ez = 1 - rz
 
                 # Add to field (only if segment inside cell).
-                if min(rx, ry, rz) >= 0 and np.max(np.abs(ar-al)) > 0:
+                if min(rx, ex, ry, ey, rz, ez) >= 0 and np.max(abs(ar-al)) > 0:
 
                     vfield.fx[ix, iy, iz] += ey*ez*x_len
                     vfield.fx[ix, iy+1, iz] += ry*ez*x_len
@@ -918,7 +918,9 @@ def min_max_ind(vector, i):
     # Ensure unity (should not be necessary).
     for field in [vfield.fx, vfield.fy, vfield.fz]:
         sum_s = abs(field.sum())
-        if abs(sum_s-1) > 1e-6:  # Normalize and warn.
+        # Normalize and warn; SHOULD NEVER HAPPEN
+        # (if it happens add it to the tests and remove the pragma-flag!
+        if abs(sum_s-1) > 1e-6:  # pragma: no cover
             msg = f"emg3d: Normalizing Source: {sum_s:.10f}."
             warnings.warn(msg, UserWarning)
             field /= sum_s
diff --git a/tests/test_fields.py b/tests/test_fields.py
index b273ec7e..2b68e3d1 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -652,6 +652,7 @@ def test_basics_diag_large(self):
         grid = emg3d.TensorMesh([h, h, h], (-3, -3, -3))
 
         # Large diagonal source in the middle
+        # x, y, z increasing
         source = np.array([[-2.5, -2.5, -2.5], [2.5, 2.5, 2.5]])
         vfield = fields._dipole_vector(grid, source)
 
@@ -672,6 +673,22 @@ def test_basics_diag_large(self):
         assert_allclose(vfield.fx[1, 1:3, 1:3].ravel(),
                         vfield.fx[2, 2:4, 2:4].ravel()[::-1])
 
+        # Large diagonal source in the middle
+        # x, z increasing, y decreasing
+        source = np.array([[-2.5, 2.5, -2.5], [2.5, -2.5, 2.5]])
+        vfield2 = fields._dipole_vector(grid, source)
+        assert_allclose(vfield.fx, np.fliplr(vfield2.fx))
+        assert_allclose(vfield.fy, -np.fliplr(vfield2.fy))
+        assert_allclose(vfield.fz, np.fliplr(vfield2.fz))
+
+        # Large diagonal source in the middle
+        # x, z decreasing, y increasing
+        source = np.array([[2.5, -2.5, 2.5], [-2.5, 2.5, -2.5]])
+        vfield3 = fields._dipole_vector(grid, source)
+        assert_allclose(vfield.fx, -np.fliplr(vfield3.fx))
+        assert_allclose(vfield.fy, np.fliplr(vfield3.fy))
+        assert_allclose(vfield.fz, -np.fliplr(vfield3.fz))
+
     def test_decimals(self):
         h1 = [2, 1, 1, 2]
         h2 = [2, 1.04, 1.04, 2]
@@ -698,13 +715,6 @@ def test_warnings(self):
         with pytest.raises(ValueError, match='Provided finite dipole'):
             fields._dipole_vector(grid, source)
 
-        # This is a warning that should never be raised...
-        hx, x0 = np.ones(4), -2
-        grid = emg3d.TensorMesh([hx, hx, hx], (x0, x0, x0))
-        source = np.array([[-2, 2, 0], [0, -2, 0]])
-        with pytest.warns(UserWarning, match="Normalizing Source: 1.25000000"):
-            fields._dipole_vector(grid, source, 30)
-
 
 @pytest.mark.parametrize("njit", [True, False])
 def test_edge_curl_factor(njit):