MATLAB: Quiver plotting arrow length

plotquivervector plotsvelocity plots

I want to plot a quiver plot of one arrow.

x=1;
y=1;
u=3;
v=4;
quiver(x,y,v,u)

I would expect that the arrow would start at point (1,1) and the length in the x direction would 3 while the length on the y direction would be 4.So the magnitude of the vector would be 5.

But this isn't the case. Can you explain me why? Thank you.

Best Answer

Two things:

(1) It looks like you swapped the u and v arguments compared to how you actually want them, so I think you actually want

quiver(x,y,u,v)

(2) There is an automatic scaling that occurs to the arrow (which is described in the documentation). You can turn off that scaling:

quiver(x,y,u,v,0)

I believe that will result in the plot you expect.

Related Solutions

MATLAB: No Arrows showing in plot When using quiver

As the grid starts from 0 and you have used this zero in the reciprocal to get (u,v) you will get inf in the u,v.; quiver uses maximum value of u and v to scale the arrows and plot. Try to repalce inf with some other value or avoid zero.

[x,y] = meshgrid(1:0.2:5,1:0.2:5);
u = 2./x;
v = 2.*y./(x.^2);
figure
quiver(x,y,u,v,1,'r')

MATLAB: How to plot reference arrow in quiver plot

I would just add an extra arrow of given length to the vector field:

% random array of vectors
x=[1:6]; y=[1:5];
u = rand(numel(y),numel(x));
v = rand(numel(y),numel(x));
% create an extra entry for the reference arrow
x = [x max(x)+1];
u = [u NaN(numel(y),1)]; u(1,end) = 1;
v = [v NaN(numel(y),1)]; v(1,end) = 0;
figure
quiver(x,y,u,v)
text(max(x),1,'1 m/s','verticalalignment','bottom')

Best Answer

Related Solutions

MATLAB: No Arrows showing in plot When using quiver

MATLAB: How to plot reference arrow in quiver plot

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