Calculate the angle between multiple points

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I have a matrix A contain x values in the first column and y values in the second column. I want to calculate the angle between vectors.
  1 Comment
Jan
Jan on 13 Jun 2013
There is no "angle between points". Do you mean the angle between two vectors?

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Accepted Answer

Jan
Jan on 13 Jun 2013
The ACOS and the corresponding ASIN approchs are numerically instable near to multiples of pi (half). Better use the more accurate ATAN2 method:
angle = atan2(norm(cross(v1,v2)), dot(v1,v2));
  4 Comments
Stephen Devlin
Stephen Devlin on 16 Mar 2018
Hi, I have no idea if anyone will see this comment as it is years after the original post, but mathematically what is this expression:
"angle = atan2(abs(det([v1;v2])),dot(v1,v2));"
Jess Smith
Jess Smith on 3 Dec 2018
@stephen thats basically doing the inverse tangent of the cross product of 2D vectors over the dot product of those vectors, giving you the angle; cross product of a x b is |a||b|sin(theta) and dot product is |a||b|cos(theta) so dividing them by each other and taking inverse tan is the angle

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More Answers (1)

michael scheinfeild
michael scheinfeild on 9 Jul 2014
what is v1 v2 can yo give example

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