Matlab angle between two points [duplicate]

Question

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Angle between two vectors matlab (6 answers)

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I am looking for an algorithm to calculate the angle between two points (defined by x and y valaue) in an image. The angle should be between the horizontal-line of one of these points and the line that connects the two points.

How can I do that?

Answer 1

For points (x1,y1) and (x2,y2) use this:

atan2(y2-y1,x2-x1)

This will return the angle between a horizontal vector from (x1,y1) to (x1+1,y1) and the vector from (x1,y1) to (x2,y2).