From 68c9f207c1a2a6bcc5fb63dae82dd0129891bd28 Mon Sep 17 00:00:00 2001
From: Thomas Albers Raviola <thomas@thomaslabs.org>
Date: Thu, 11 Jul 2024 10:10:01 +0200
Subject: Add bondi.mac

---
 bondi.mac | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 bondi.mac

diff --git a/bondi.mac b/bondi.mac
new file mode 100644
index 0000000..3577589
--- /dev/null
+++ b/bondi.mac
@@ -0,0 +1,37 @@
+debugmode: true;
+
+linel: 150;
+
+load("ctensor");
+
+dim: 4;
+cframe_flag: false;
+ct_coords: [u, r, theta, phi];
+
+depends([U, V, _beta, _gamma], [u, r, theta]);
+
+lg : zeromatrix(4, 4);
+lg[1, 1] : V * r^-1 * exp(2 * _beta) - U^2 * r^2 * exp(2 * _gamma);
+
+lg[1, 2] : exp(2 * _beta);
+lg[2, 1] : exp(2 * _beta);
+
+lg[1, 3] : U * r^2 * exp(2 * _gamma);
+lg[3, 1] : U * r^2 * exp(2 * _gamma);
+
+lg[3, 3] : - r^2 * exp(2 * _gamma);
+lg[4, 4] : - r^2 * exp(- 2 * _gamma) * sin(theta)^2;
+
+/* Load metric and compute inverse */
+cmetric();
+
+/* For some reason some components must be simplified by hand ... */
+ug[2,2] : expand(ug[2,2]),simp;
+
+/*
+    Calculate Christoffel symbols
+    mcs[i, j, k]: Christoffel symbols of the second kind (one upper index - k)
+*/
+
+christof(false);
+ricci(false);
-- 
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