From c1a0ba182830b2dd526bf866f83dd22ad2f8fa64 Mon Sep 17 00:00:00 2001
From: Nikolaus Demmel <demmeln@in.tum.de>
Date: Fri, 3 Nov 2017 21:25:12 +0100
Subject: [PATCH] Fix SO(3) exponential for small angles.

- The Taylor expansion is missing a factor of 1/4, to go from theta_sq
  to theta_hald_sq.
---
 sophus/so3.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sophus/so3.hpp b/sophus/so3.hpp
index 7cd6064b9..7a0d937fc 100644
--- a/sophus/so3.hpp
+++ b/sophus/so3.hpp
@@ -336,7 +336,7 @@ class SO3Base {
       imag_factor = Scalar(0.5) - Scalar(1.0 / 48.0) * theta_sq +
                     Scalar(1.0 / 3840.0) * theta_po4;
       real_factor =
-          Scalar(1) - Scalar(0.5) * theta_sq + Scalar(1.0 / 384.0) * theta_po4;
+          Scalar(1) - Scalar(1.0 / 8.0) * theta_sq + Scalar(1.0 / 384.0) * theta_po4;
     } else {
       Scalar sin_half_theta = sin(half_theta);
       imag_factor = sin_half_theta / (*theta);