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.

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Anu G 2018-12-24

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评论： madhan ravi 2018-12-27

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)

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madhan ravi 2018-12-24

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编辑：madhan ravi 2018-12-24

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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)