By: fik  fik_ 
Hi i believe i have found a error in these equations, you seem
to have the equations sent to the atan2 functions the wrong way
round in both. 
By: Martin Baker  martinbaker 
I tried converting heading =10 deg, attitude=20 deg, bank=30
deg 
By: fik  fik_ 
I am using the first method on your euler to quaternion page
and i do not get the same values as you for qx qy unless i change
the signs at center all to  . 
By: Martin Baker  martinbaker 
As you pointed out, I made a mistake in the calculations on my
last post, I've now corrected the sign and the round trip
calculation (euler > quaternion > euler) now gives the
correct result to the nearest degree. See calculations
below. An OpenOffice.org with the following is here

By: fik  fik_ 
Hi thanks for that explaination. Yes the problem was mine, i
was using atan2 in Excel to which defines atan2 as: 
By: fik  fik_ 
Well i just had to post an apology to microsoft i just googled 'atan2 definition' and it seems no absolute answer which should be. What a mess for a math function thought they would all be standadised by now. May i suggest a little note added somewhere on page about this potential confusion might save some body else the haed ache this gave me. Many thanks for your help.Anyway glad your pages where correct keep them going as i have found them very helpful in understanding a lot of things 
By: Martin Baker  martinbaker 
> May i suggest a little note added somewhere on page about
this potential 