I keep getting a 'parse error' at '='

• All my equal signs are underligned saying that there's a parse error, can someone help me with this?

function [r,theta] = polar_coordinates(x,y)

r = sqrt ((x^2)+(y^2))

if(x>0)
    theta = arctan(x/y)
end

if (x<0)
    if (y>0)
        theta = arctan(x/y) + pi
        if (y<0)
            theta = arctan(x/y) - pi
            if (y=0)
                theta = pi
            end
        end
    end
end

Answer 1

[Bruno Luong]

Test wth "=="

if (y==0)

[Nadine Nassar]

Thanks a lot!!