[Closed] AngleAxis rotation thingies

Hello people,

I got a large list (.txt) file that has all sort of coordinates in them.
i read it, put it into an array and for each frame set de position accourding to the position in the text file.

al good so far.

But rotation is a bit trickier.

i calculate rotation thrue:
x = x1 – x2
y = y2 – y1
rot = atan2 y x

think this is correct.
now in the loop where i set the position i also set the rotation.
But if i do this:
rot_obj = eularangles 0 0 rot
rotate myObj rot_obj

the object gets rotated but not correctly,
Example first rotation is 40.12
second is : 42.67
what happends is that the object gets rotated 82.69 (first it is rotated by the first value, next by the second) wich is not correct.

So how to i set the rotation of a object without incrementing the values.
thus first rotation is 40.12, then next frame total rotation is 42.67 ???

Thx in advance!