I am trying to draw 2D streamline from a vector field with matlab software, but I got spiral shape, which is not right. Is there any way to avoid that.

a=3; n=30;

xt = linspace(-a, a, n); yt = linspace(-a, a, n);

[x,y] = meshgrid(xt, yt);

quiver(x,y,y,-x,5) axis image

hold

h=streamline(stream2(x,y,y,-x,2,0)); set(h, 'Color', 'red');

hold

I run your code and I think every think is OK.

The stream lines seems to be tangent to the vector field. Why do you say that the spiral shape is wrong?

What I expect was a closed circle.

Right. Stream lines cannot spiral in 2D unless there is a source or sink. They must close on themselves, or begin and end on a boundary. In this case they must be circles.

I got it by using stream function