Why am I only getting partial streamlines.

I am trying to plot streamlines to look like this

But I am only getting part way

I have tried changing my sy and sx multiple times but it just changes what part shows up. I have no idea what I'm doing wrong

Here's my code

%% 
[X,Y] = meshgrid(-5:0.5:5); 

sx = linspace(-5,5,20); 
sy = sx;
% sx = (-5:0.5:5); 
% sy = ones(size(sx)); 
 sy = sx./sx; 
% [SX,SY] = meshgrid(sx,sy); 



%let U = e1 & V = e2
U = Y; 
V = X; 


figure()
hold on 
quiver(X,Y,U,V); 
streamline(X,Y,U,V,sx,sy,[0.1,20000]); 

Answer 1

[David Goodmanson]

Hi Boris,

the problem is the line sy = sx./sx which creates a vector of ones for sy. Then every streamline originates at the horizontal line sy =1. Here is an example that draws the streamlines orginating from the left side (upper half) and the top side (left half); the remining two sides are similar.

[X,Y] = meshgrid(-5:0.5:5); 
sx = linspace(0,5,10); 
sx(end) =[];      % eliminate streamlines originating at the corners 
sy = sx;
onx = ones(size(sx));
ony = ones(size(sy));

U = Y; 
V = X; 
figure()
hold on 
quiver(X,Y,U,V); 
streamline(X,Y,U,V,-5*onx,sy,[0.1,20000]);
streamline(X,Y,U,V,-sx, 5*ony,[0.1,20000]);
hold off

[Boris Chan]

Oh I see so your answer gives half, so since I have 4 quadrants I have to repeat the streamline function 4x with different parameters?

[David Goodmanson]

yes, that's right.