direction of quiver arrows

I was using quiver to plot a vector field. The details of the code is not relevant here. As can be seen from the figure the vector [-21,-21] is pointing 45 from the positive horizonta when it should be in the reverse direction. Why?

[David Goodmanson]

Hi F,

hard to see with the label being there, and the lack of horizontal and vertical scales is not helping. Could you change the plot a bit?

[F46]

Thanks for replying. This is another figure. The horizontal and vertical scales are visible. The original figure is seen on the right. I ran the same code with the sign of the vector components reversed but got the same image. With [21,21] and [-21,-21] pointing in the same direction. I am not sure why?

[Rik]

Try to make a MWE so we can run your code without any other dependencies and can reproduce your issue. Are you able to see the direction of the selected vector? I can zoom in all I want, but I can't see it.

[F46]

Thanks Rik and David. I am grateful for your replies. Here is a piece of code that will prouce this figure

r0=1;v0=1.0;npoints=10;scale=1.5;x=linspace(-scale*r0,scale*r0,npoints);
 [x,y]=meshgrid(x);u=x.*x+y.*y-r0*r0;vx=-4*v0*u.*x;vy=-4*v0*u.*y;
 quiver(x,y,vx,vy,0);

[Rik]

I don't see your issue.

quiver(1.5, 1.5, -21, -21),axis([-20 20 -20 20])

[F46]

Thanks Rik. I guess I was looking at the wrong vector