From 6440b408ac0955f3b5a5e94ed7a9d68ba2df62e4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gonzalo=20Jos=C3=A9=20Carracedo=20Carballal?=
 <BatchDrake@gmail.com>
Date: Mon, 6 Mar 2023 20:36:50 +0100
Subject: [PATCH 1/3] Implement mesh_estimate_cfl_timestep

---
 python/openEMS/automesh.py | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/python/openEMS/automesh.py b/python/openEMS/automesh.py
index 93472fa..734201a 100644
--- a/python/openEMS/automesh.py
+++ b/python/openEMS/automesh.py
@@ -75,3 +75,26 @@ def mesh_hint_from_box(box, dirs, **kw):
             hint[ny].append(start[ny])
     return hint
 
+def mesh_estimate_cfl_timestep(box):
+    """ mesh_estimate_cfl_timestep(box)
+
+    Estimate the maximum CFL time step of the given box needed to ensure numerical stability,
+    assuming propagation in pure vacuum.
+
+    :returns: the maximum CFL time step, in seconds
+    """
+    minDiff = [None, None, None]
+    for ny in range(3):
+        lines = box.GetQtyLines(ny)
+        for i in range(1, lines):
+            delta = box.GetLine(ny, i) - box.GetLine(ny, i - 1)
+            if minDiff[ny] is None or delta < minDiff[ny]:
+                minDiff[ny] = delta
+    if None in minDiff:
+        sys.stderr.write('FDTD::automesh: Warning, mesh is ill-defined (no lines in certain directions?)\n')
+        return 0
+
+    delta_t = box.GetDeltaUnit() / (C0 * np.sqrt(np.sum(np.array(minDiff) ** -2)))
+
+    return delta_t
+

From 3eb44399592ceca143c8b0b0a873faef3601cdb1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gonzalo=20Jos=C3=A9=20Carracedo=20Carballal?=
 <BatchDrake@gmail.com>
Date: Mon, 6 Mar 2023 21:45:17 +0100
Subject: [PATCH 2/3] Improve readability of mesh_estimate_cfl_timestep

---
 python/openEMS/automesh.py | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/python/openEMS/automesh.py b/python/openEMS/automesh.py
index 734201a..c3da361 100644
--- a/python/openEMS/automesh.py
+++ b/python/openEMS/automesh.py
@@ -75,26 +75,19 @@ def mesh_hint_from_box(box, dirs, **kw):
             hint[ny].append(start[ny])
     return hint
 
-def mesh_estimate_cfl_timestep(box):
-    """ mesh_estimate_cfl_timestep(box)
+def mesh_estimate_cfl_timestep(mesh):
+    """ mesh_estimate_cfl_timestep(mesh)
 
-    Estimate the maximum CFL time step of the given box needed to ensure numerical stability,
+    Estimate the maximum CFL time step of the given mesh needed to ensure numerical stability,
     assuming propagation in pure vacuum.
 
     :returns: the maximum CFL time step, in seconds
     """
-    minDiff = [None, None, None]
+    invMinDiff = [None, None, None]
     for ny in range(3):
-        lines = box.GetQtyLines(ny)
-        for i in range(1, lines):
-            delta = box.GetLine(ny, i) - box.GetLine(ny, i - 1)
-            if minDiff[ny] is None or delta < minDiff[ny]:
-                minDiff[ny] = delta
-    if None in minDiff:
-        sys.stderr.write('FDTD::automesh: Warning, mesh is ill-defined (no lines in certain directions?)\n')
-        return 0
+        invMinDiff[ny] = np.min(np.diff(mesh.GetLines(ny))) ** -2
 
-    delta_t = box.GetDeltaUnit() / (C0 * np.sqrt(np.sum(np.array(minDiff) ** -2)))
+    delta_t = mesh.GetDeltaUnit() / (C0 * np.sqrt(np.sum(invMinDiff)))
 
     return delta_t
 

From cf34998b015caa433bdf238914349c99474b120e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gonzalo=20Jos=C3=A9=20Carracedo=20Carballal?=
 <BatchDrake@gmail.com>
Date: Mon, 6 Mar 2023 21:46:43 +0100
Subject: [PATCH 3/3] Add missing import

---
 python/openEMS/automesh.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/python/openEMS/automesh.py b/python/openEMS/automesh.py
index c3da361..51bf0cb 100644
--- a/python/openEMS/automesh.py
+++ b/python/openEMS/automesh.py
@@ -10,6 +10,7 @@ import numpy as np
 
 from CSXCAD import CSPrimitives
 from CSXCAD.Utilities import CheckNyDir, GetMultiDirs
+from openEMS.physical_constants import C0
 
 def mesh_hint_from_primitive(primitive, dirs, **kw):
     if primitive.GetType() is CSPrimitives.POINT: