DCM info: https://code.google.com/p/ardu-imu/wiki/Theory C++ implentation http://webbot.org.uk/WebbotLibDocs2/49646.html https://github.com/jmesmon/imu_9drazor/blob/master/src/SF9DOF_AHRS/SF9DOF_AHRS.pde
Kalman filters http://autopilot.sourceforge.net/kalman.html
Add more info
Quaterion example in python http://www.gamedev.net/page/resources/_/technical/math-and-physics/quaternion-powers-r1095 http://forums.xkcd.com/viewtopic.php?f=11&t=72233 http://science-o-matics.com/2014/01/how-to-python-scripting-in-blender-8-rotation-mit-quaternionen/
Explanation of magnetic compass error due to tilt https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CDEQFjAC&url=http%3A%2F%2Fwww.pnicorp.com%2Fsystem%2Ffiles%2FWhite%2520Paper%2520-%2520Tilt-Induced%2520Error%2520in%2520a%25202-Axis%2520Compass%2520r02_Dec-11.pdf&ei=BBrzU-SHCvKR0QXbuYH4CQ&usg=AFQjCNHxvS4iax0mSBH64Mx7Apt7pyVdXQ&sig2=UvAjNTDFVtyyD4ORWXCGqQ
http://www.parallax.com/sites/default/files/downloads/29133-Compass-Module-Application-Note.pdf