Hi, I am trying to plot the following equation. Its showing error in mod function. Kindly clarify me how to use the mod function to get the proper output.

theta=0:10:90;
rho=0.465;
%d=25; wrong
%k=0.99*(1+(1i*0.66)) ;
k=real(0.97+0.6402i);
poftheta=sqrt((k.^2)-(cos(theta).^2));
y=(rho*sin(theta))./(poftheta);
roftheta=((y-1)/(y+1));
r0=-20*log10(mod(roftheta));
hold on
grid on
plot(theta,r0)

Answer 1

[madhan ravi]

It should be abs instead of mod (assuming that you want to convert the negative sign to positive sign ? )

theta=0:10:90;  % Note: if you reduce the step size you will get a smoother plot
rho=0.465;
%d=25; wrong
%k=0.99*(1+(1i*0.66));
k=real(0.97+0.6402i);
poftheta=sqrt((k.^2)-(cos(theta).^2));
y=(rho*sin(theta))./(poftheta);
roftheta=((y-1)./(y+1));
             % ^---- missed dot
r0=-20*log10(abs(roftheta));
            % ^----- here
grid on
plot(theta,r0)

[madhan ravi]

what do you expect the result of mod ?? it returns the remainder of the first argument (divident) and second argument (divisor) , did you read the link I shared in the answer.

The only way to plot the complex number is to plot it's real part vs the imaginary part or vice versa.

[Anu G]

Thank you sir

[madhan ravi]

Anytime :)