How to know how points are from the same line?

I have set of points. I want to check how many of them belong to the same line or the end coordinates of each line.

For example I have matrix A= [1 2; 3 4; 5 6] and I want to check the above.

For example i need to know about 5 points of the four different lines. (starting or end of each of the four)

[John D'Errico]

What does A have to do with the picture that you show? There seems to be no obvious relation. If you want an answer, then you need to explainCLEARLY what you are looking to do.

Answer 1

[KSSV]

If you have a set of points, to determine whether they fall/ lie along a straight line, calculate the area...if area is zero then the points lie along a straight line. You can get the area give a set of points using polyarea.