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-reflect pts through x axis -reflect pts through y-axis -reflect pts through ori

ID: 3545477 • Letter: #

Question

                    -reflect pts through x axis                 

                    -reflect pts through y-axis                 

                    -reflect pts through origin

                    -reflect points through the line y=x                 

                    -rotate (theta) degrees CC                 

                    -scale x and y according to a scale factor (determined by me)                 

                    -shear parallel to x-axis (with shear factor k set by me)                 

                    -shear parallel to y-axis (again, with self determined shear factor                 

                    Each of these is to be a seperate function with its own file. A given example (that I know works) for reflect through x-axis is as follows:                 

                    function pts = reflectx(pts)                 

                    % reflect 2 X N matrix of points through the x-axis                 

                    mat = [1 0; 0 -1]                 

                    pts = mat * pts;                 

                    end                 

                    So what I need help with is modifying the above to work with each transformation. I have my versions of them worked out but they don't seem to be wokring when                    I call them. I am mostly interested in the "mat = [x y; x y]" line for each case. Please be clear as I'm not the greatest at matlab. Thank you very much.

Explanation / Answer

1) through y axis -> mat = [-1 0; 0 1]   

2) x axis -> mat = [-1 0; 0 -1]   

3) x=y line -> mat = [0 1; 1 0]   

4) theta CC -> mat = [cos(theta) sin(theta); -sin(theta) cos(theta)]   

5) scale x and y -> mat = [c 0; 0 d] where c,d are x and y scaling respectively   

6) shear parallel to x axis -> mat = [k 0; 0 1]   

7) shear parallel to y axis-> mat = [1 0; 0 k]

Let me know if you have problem and plz rate if it helps.