MATLAB: Finding the point

Question

I know the equation of a line N. there is a point P =(a,b) lying on the same plane. (not in that line) how can i find whether that point (a,b) lies right hand side of that line N or lefthand side? shall i find that by finding the normal vector to that line N

Answer 1

Right or left hand side means above or under the line?

If so:

line_eq = k*x + n
P = (a,b)
if k*a + n > b
'under the line'
elseif if k*a + n < b
'above the line'
else
'on the line'
end