Why Matlab is not plotting anything in my figure?

[EDIT: 200110710 16:40 CDT - reformat - WDR]

I wrote a program and want to plot Zr as a line connecting dots for every whole degree from 0 to 360 degrees or 2*pi radians. I am not seeing anything when I run the following program:

%-------------------------------------------------------------------------------------------------------------------------------------

clear , clc ;

m = 0.25;                       % locus of the impedance “seen” by relays
Z = input('impedance is 0.1i or 0.025 + 0.1i ');  % constant impedance
Ea = 1;                         % set Ea at 1 Per-Unit for simplicity
Eb = Ea / input('voltage behind Zeq = Zm ratio is 1.15 or 0.87 ');
Zm = m * Z + (1 - m) * Z;          % equivalent impedance

d = 0;
increment = pi / 180;
end_count = 2 * pi;

for d = 0: increment : end_count;

d;              % values of d in radians

I = ( Ea * cos(d) + Ea * 1i * sin(d) - Eb ) / Z; 
% current of the circuit

E = ( 1 - m ) * (Ea * cos(d) + Ea * sin(d) * 1i + m * Eb);  
%Voltage seen by relay

Zr = E / I;                         % impedance seen by the relays at m

r = abs(Zr);
the = angle(Zr);

end

figure ( 1 );
set (gca, 'FontSize', 12)
whitebg('white')
polar (r, the, 'red'), grid on
xlabel ('Impedance, Zr, Seen By Relay [Per-Unit]','FontSize',14);
ylabel ('Polar Coordinates / Compass Plot','FontSize',14);

Answer 1

[Walter Roberson]

Each time through the loop, you are overwriting "r" and "the", so at the end of the loop they have only scalar values and only a single point is being plotted.

You should consider vectorizing your loop, or you should learn how to use arrays and loop indices.

[Daniel]

Thanks Walter. I googled info on vectorizing my loop and am trying to apply it to my program and still can't get it to work. In hindsight, I should've asked for suggestions in how to correct that part of my program. Can you show me how to fix it?

[Naresh]

n=1;

for d = 0: increment : end_count;

d; % values of d in radians

I = ( Ea * cos(d) + Ea * 1i * sin(d) - Eb ) / Z;

% current of the circuit

E = ( 1 - m ) * (Ea * cos(d) + Ea * sin(d) * 1i + m * Eb);

%Voltage seen by relay

Zr = E / I; % impedance seen by the relays at m

r(n) = abs(Zr);

the(n) = angle(Zr);

n=n+1;

end

%work for you?

[Walter Roberson]

d = 0: increment : end_count;

I = ( Ea * cos(d) + Ea * 1i * sin(d) - Eb ) / Z;

E = ( 1 - m ) * (Ea * cos(d) + Ea * sin(d) * 1i + m * Eb);

Zr = E ./ I;

r = abs(Zr);

the = angle(Zr);

[Daniel]

I'm getting the plot to work now. Thank you both for responding.