Search:

See my second post. When C and A point to the same array you will modify A when you write to C thus corrupting your calculations.

Just hit me when i was preparing some dinner (yah yah my mind is weird sometimes...). I'm almost willing to bet money the problem is the second mult, where resultQuaternion works as both input and...

Perform the calculation by hand first, with pen and paper (and check to make sure you get the correct result). Then step through the code with a debugger and check where you get the wrong values.