Plotting polar graphs with Matlab

Hi, I am using Matlab to generate symmetric polar plots on the lower half of the circle (i.e. 0-83 degrees and 277-360 degrees).

h = polar(phi,rho)

where phi and rho are input text files.

In this case, Matlab connect the point of (phi_83,rho_83) to (phi_277,rho_277) with one straight line. How can I modify it so that they don't get connected?

Thanks a lot, Bahar

Answer 1

[Star Strider]

You have to break them up into two separate plot calls, and use the hold function:

phi = [linspace(0, 83)  linspace(277, 360)]*pi/180;     % Create Data
rho = abs(sin(6.5*phi));                                % Create Data

figure(1)
polar(phi(1:100), rho(1:100))
hold on
polar(phi(101:200), rho(101:200))
hold off

The linspace function creates a 100-element vector by default. You can change that with a third argument, but you would have to change the subscripts in the polar calls to match the new vector lengths.

[Bahar]

Thanks a lot. This is a great solution :)

Bahar

[Star Strider]

My pleasure! Thank you for the compliment!

Another possibility (but probably not always applicable) is to insert NaN values in both vectors. (Here, ‘rho’ will include them automatically, because it’s calculated from ‘phi’.)

For example:

phi = [linspace(0, 83) NaN linspace(277, 360) NaN]*pi/180;  % Create Data
rho = abs(sin(6.5*phi));                                    % Create Data

figure(1)
polar(phi, rho)