For the transformation used see
http://de.wikipedia.org/wiki/Sekans_Hyperbolicus_und_Kosekans_Hyperbolicus#Komplexes_Argument
(German only)

Change-Id: If502b7333308069d7fcbe09e954b26ce8b7268b6
(cherry picked from commit b884c2e0)
Reviewed-on: https://gerrit.libreoffice.org/1926Reviewed-by: Kohei Yoshida <kohei.yoshida@gmail.com>
Tested-by: Kohei Yoshida <kohei.yoshida@gmail.com>