3d rotation of accelerometer vectors

[IMK]

Hello,

I have some accelerometer vector data A (3d vectors x,y,z ) than I have normalized so I guess they are unit vectors. Now what I what to do is to 3d rotate them by another set of normalized accelerometer vector data B so I get a third set of vectors D.

I have tried a simple vector subtraction but this does not seem to work, so can you tell me please what math method I should be using for the please?

Is it Euler angles, Cartesian etc etc.

A method of how to do it would be wonderful, and I know this is not a programming forum but if anyone knows of some c/c++ source for this is would be great.
Many thanks IMK

 

[fresh_42]

Not quite sure what you mean by a rotation by three vectors. I assume a rotation along one axis, then another and finally a third one. Express these three rotations in an Cartesian standard frame: an orthonormal system $x,y,z$. Then build a matrix $A$ with your initial vectors as columns. One rotation is then a matrix multiplication from the left with a rotation matrix $R_i$. The result is then $R_3R_2R_1A$.

The first step, expressing your rotations in an $x,y,z$ frame is, because rotations along these axis are especially easy. You can look them up on Wikipedia for instance.