Random Vertical Lines in Contour Plot. HELP! SRS

Hello all, I am having trouble with making a contour plot . Each time I run the code I get vertical lines throughout the plot.

clear all;close all;clc;
a=1; b=1.5; %a<b
c=a*a/b;
S=10/(2*pi);

[x,y]=meshgrid(linspace(-2,2,100),linspace(0,2,100));
theta1=atan(y./x); %for sink at origin
theta2=atan(y./(x-c)); %for source at (a^2 /b ,0)
theta3=atan(y./(x-b)); %for source at (b,0)

psi=S*(-theta1 + theta2 + theta3);

contour(x,y,psi);

Problem is similar to (though no solution was provided) http://www.mathworks.com/matlabcentral/answers/20951-contour-plot-problem

Any help appreciated!! Thanks

Answer 1

[Adam Weiss]

It should look like: