# images

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• commit e16ac8ccf65ac4d7e5f306a76181c7eae9efaa9c
parent 804e5dda60c1e2d14635ebe5951b0f8666d11608
Author: Pablo <pablo-escobar@riseup.net>
Date:   Sun, 26 Sep 2021 20:23:11 +0000

Updated the labels and the description of the picture of quaternion rotations

Diffstat:
Mquaternion-rotation.tikz | 12+++++++-----

1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/quaternion-rotation.tikz b/quaternion-rotation.tikz
@@ -1,15 +1,17 @@
-% This drawing represents the correspondance between conjugation by unitary
-% quaternions and rotations in the 3-dimensional euclidian space
+% This drawing represents the correspondance between conjugation by pure
+% unitary quaternions and rotations in the 3-dimensional euclidian space: the
+% coordinates of a unitary quaternion p number with zero real cofficient induce
+% a line through the origin in the 3-dimensional enclidian space, and
+% conjugation by cos t + p sin t acts as rotation by 2 t around this axis.
\begin{tikzpicture}
% The rotation axis
\begin{scope}[rotate=-60]
% The axis
-    \draw[->] (0, 0) -- (0, 2.5) node[right]{$\mathrm{Im}\,q$};
+    \draw[->] (0, 0) -- (0, 2.5) node[right]{$p$};

% The rotation
-    \draw[->] (0.43, 2) node[right]{$\theta=\frac{\arccos(\mathrm{Re}\,q)}{2}$}
-                        arc (30:360:0.5 and 0.25);
+    \draw[->] (0.43, 2) node[right]{$2 \theta$} arc (30:360:0.5 and 0.25);

% The origin and the intersection of ratation axis with the unit sphere
\filldraw (0, 0) circle (1pt) (0, 1) circle (1pt);