Angles between 3 vector in 3d

Hi I am trying to find angle between 3 vectors;

Terminal vector:-0.063695 -0.588189 2.333766

1. vector: 0.008239 -0.640457 2.295980 2.vector: -0.024011 -0.216596 2.461521

Could anyone help me?

Thanks in advance

Answer 1

[Mischa Kim]

You can make use of the dot product (between vectors):

vec1     = [-0.063695  -0.588189  2.333766];
vec2     = [0.008239  -0.640457  2.295980];
angle_12 = acos(dot(vec1,vec2)/(norm(vec1)*norm(vec2)))

and similar for the other pairs of vectors.

[barbar]

Thank you for your response but I ve already tried that command. Actually I misrepresented my problem.

Right know I have three positions and each one is in the 3d space. The origin of these positions is terminal position. So I want to find the angle between these positions which is created by first and second positions on terminal position. Sorry about my poor writing skills but I hope I express myself clearly. Thanks again

[Mischa Kim]

I see...

vec     = [-0.063695  -0.588189  2.333766];
vec1    = [0.008239  -0.640457  2.295980];
vec2    = [-0.024011  -0.216596  2.461521];
dv1     = vec1 - vec;
dv2     = vec2 - vec;
angle_12 = acos(dot(dv1,dv2)/(norm(dv1)*norm(dv2)))

[barbar]

Thank you.I guess displacement calc. should work for my situation.

Answer 2

[Roger Stafford]

The 'atan2' function is more accurate than 'acos' for vectors that are nearly parallel. For two 3D vectors v1 and v2, do this:

 ang = atan2(norm(cross(v1,v2)),dot(v1,v2));

This angle will be in radians.