Quiver plot when axes scale are too different result in very ugly plots

Hey. I am trying to make a nice-loking quiver plot, but because the axes are in different scales the quiver plot looks very messy. My specific problem is that

1). The arrow heads look wide open and assymetrical.

2). The lengths of the arrows are all normalized to 1, but yet some do look much longer than others due to the different axes scales.

The attached figure can be reproduced by typing

quiver(log10(VN),PSIN,vdot,psidot,0.5)

where the relavant variables are attached in the .mat file below. I have already tried a variety of things including the "quiverInLogScale.m" and "arrow3.m" File Exchange functions, but neither seem to help. Thank you so much for any help!

Answer 1

[Chunru]

load("quiverPlotVariables.mat")
whos

  Name         Size            Bytes  Class     Attributes

  PSIN        10x10              800  double              
  VN          10x10              800  double              
  ans          1x48               96  char                
  psidot      10x10              800  double              
  vdot        10x10              800  double              

% You need to scale the vdot and/or psidot so that they are representing
% the true orientation of the vector.  Assume that vdot and psidot has same
% unit, then you can chek a squared size area, eg. x=[-9:-8.5] and y=[0.64
% 0.68], which is approximately a square.   The ratio of width to length is
% thus 0.5/0.02=25
quiver(log10(VN), PSIN, vdot, 25*psidot, 0.2)

% Perhaps a better method is to use the index as x- and y-axis
% Don't know the meaning of your variable.  Assume that vdot and psidot
% give the correct direction (meaning same unit).
% 
[m, n]= size(VN);
[xx, yy] = meshgrid(1:n, 1:m);
figure;
quiver(xx, yy, vdot, psidot, 0.5); 
axis equal

% Then you can change the x- and y- ticklabel to whatever you want.

[Axel Wong]

Hey Chunru,

Thanks for your answer. However, it seems your vectors are still of different lengths. Do you know if it's possible to just plot an arrow of equal size at the meshgrid grid points (here the end of the arrow stem)? I know in my case it's impossible to get a nice-looking figure if I still want to incorporate a sense of magnitude to the lengths of my vectors (as their magnitudes are several orders of magnitudes different) so I am willing to just show their directions.

Thanks!

[Chunru]

Updated above.