Calculating Angles between connected line segments using MATLAB -

i'm using matlab first time, , have little experience programming.

i have 3 coordinate points connected line segments create sort of zig-zag path. if line segment origin first point extended past first point, need find angle measure line extending first point line extending first point second point. needs done second third point well. i've read solutions of similar questions, wasn't able interpret , modify them situation.

let's coordinates are:

coord = [1 2; 2 4; 1.5 1; 4 2] coord =     1.0000    2.0000     2.0000    4.0000     1.5000    1.0000     4.0000    2.0000 

this give following zig-zag pattern:

to find angles of each line segment, can following:

coord_diff = diff(coord) %// find difference between each                           %// coordinate (i.e. line between points)  %// make use of complex numbers. vector  %// given x + i*y, imaginary unit vector = coord_diff(:,1) + 1i * coord_diff(:,2);  line_angles = angle(vector) * 180/pi; %// line angles given in degrees   diff_line_angle = diff(line_angles)   %// difference in angle between each line segment 

this gives following angles, upon inspection of graph seems reasonable.

line_angles =        63.4349   -99.4623    21.8014  diff_line_angle =  -162.8973   121.2637 

update after comments

coord = [0 0; 3 4; -1 7; 3 10]    coord =      0     0      3     4     -1     7      3    10  coord_diff = diff(coord) %// find difference between each                           %// coordinate (i.e. line between points) coord_diff =      3     4     -4     3      4     3 %// angles of these lines approximately 36.86 , 53.13 degrees  %// make use of complex numbers. vector  %// given x + i*y, imaginary unit vector = coord_diff(:,1) + 1i * coord_diff(:,2);  line_angles = angle(vector) * 180/pi; %// line angles given in degrees line_angles =    53.1301   143.1301    36.8699     

i'm not sure how want treat different signs etc., should work:

[90-line_angles(1), arrayfun(@(n) line_angles(n+1)-line_angles(n), ...     1:numel(line_angles)-1)].' ans =    36.8699    90.0000  -106.2602 

this simpler, harder adapt in case need change signs or similar:

[90-line_angles(1); diff(line_angles)]