better visualization of quiver()

Hello!

I have some velocity-field, which I am trying to visualize by this code:

quiver(x,y,Vx,Vy);

Vx and Vy are arrays of 102x102 demensions. It all worked, but I get this:

If maximaze it by 8 and zoom to right up corner then the field seems to be possible to analyze:

So, how to spread evenly it all on coordinate plane, how to make arrays less and increase distance between them in order to achieve better understanding of the whole picture at once?

Thank you in advance!

Answer 1

[Star Strider]

Without knowing more about what you are doing, one option would be:

quiver(x(1:5:end), yx(1:5:end), Vxx(1:5:end), Vyx(1:5:end), 0)

This plots fewer points (and arrows), and the ‘0’ turns off all arrow scaling. Delete the ‘0’ and replace with another number to keep the scaling and set the arrow length.

[Star Strider]

Ivan Volodin’s Answer moved here:

Thank you! Is there a way to make distance between arrows, belonging to different points on coordinate plane, bigger?

[Star Strider]

My pleasure!

One option is to increase the step size from 5 to a larger value:

sv = 10;                                                            % ‘Step’ Value
quiver(x(1:sv:end), yx(1:sv:end), Vxx(1:sv:end), Vyx(1:sv:end), 0)

Another way would be to set the scaling factor (that you have already done), turn autoscaling off, and several other options.

See Quiver Properties (link) for a list of everything about the arrows you can customise.

A third option would be to add a contour plot, so you could present the same information and require fewer arrows. See the documentation on Combine Contour Plot and Quiver Plot (link).

[Jacob Ivanov]

If you, like I was sitting here wondering why this wasn't working, and you got an error similar to

Error using quiver. The size of X must match the size of U or the number of columns of U.

Make sure that if you are using an x, y array that are one-dimensional, whereas u, v are two-dimensional arrays, you do something similar to this:

quiver(x(1:16:end), y(1:16:end), u(1:16:end, 1:16:end), v(1:16:end, 1:16:end))