When i solve this equation, i get a surface with a slant! I dont know what is the problem, can anyone fix it?

My program involves bessel functions in polar coordinates (r,theta). The equation to solve is:

z(r,theta)=(Besselj(1,r)+1.90187*r).cos(theta)

I wrote the folowing code:

[th,r] = meshgrid((0:5:360)*pi/180,0:.05:1);
z=(besselj(1,r)+1.90187.*r).*cos(th);
[X,Y,Z] = pol2cart(th,r,z);
surf(X,Y)

1. I would like to know whether my program code is correct to sovle the equation and
2. When i solve it, i get a plot that is slanted. Is there somethingn wrong with my code?

Thanks, any help will be highly appreciated.

Answer 1

[Grzegorz Knor]

First of all, the radius r in polar coordinates must be non-negative.

[Nanda]

I did ofcourse alter the range of values of r from 0:0.05:1, but i get the same slant.