From 0bd39dc4022856aba91fbd2762c321765111baf8 Mon Sep 17 00:00:00 2001
From: Hannes <157805253+Yamneznim@users.noreply.github.com>
Date: Thu, 7 May 2026 16:08:07 +0200
Subject: [PATCH] Update geometry.py

Updated geometry.py, so that the value of c only gets changed if necessary for kappa>0. Also the sign of c is kept. Thus allowing the definition of concave lenses.
---
 tracepy/geometry.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tracepy/geometry.py b/tracepy/geometry.py
index c295d00..b4ab5f0 100644
--- a/tracepy/geometry.py
+++ b/tracepy/geometry.py
@@ -86,8 +86,12 @@ def check_params(self) -> None:
             if self.kappa is None:
                 raise Exception("Specify a kappa for this conic.")
             elif self.kappa > 0:
-                print("Warning: Specified c value is not used when kappa>0")
-                self.c = np.sqrt(1 / (self.kappa * pow(self.Diam / 2., 2)))
+                if pow(self.Diam / 2., 2) > 1/(self.kappa*pow(self.c, 2)):
+                    print("Warning: Specified c value had to be changed in accordance with the conditions of the conic euqation.")
+                    if self.c > 0:
+                        self.c = np.sqrt(1 / (self.kappa * pow(self.Diam / 2., 2)))
+                    elif self.c < 0:
+                        self.c = -np.sqrt(1 / (self.kappa * pow(self.Diam / 2., 2)))
         elif self.c == 0 and self.kappa is None:
             # Used for planes, does not affect calculations.
             self.kappa = 1.
@@ -212,4 +216,4 @@ def conics_plot(self, point: np.ndarray) -> np.ndarray:
         if self.kappa is None:
             raise ValueError("kappa must not be None for conic plot calculations")
         function[~nan_idx] = self.c * pow(rho, 2) / (1 + pow((1 - self.kappa * pow(self.c, 2) * pow(rho, 2)), 0.5))
-        return function
\ No newline at end of file
+        return function