At line [gnum4,gde​n4]=series​(gnum3,gde​n3,numK,de​nK); I have an error called transfer function not proper and I can not figure out why this error is occuring

for kd = 0:1:10;
    for kp = 0:1:10;
        m = 0.01;
        g = 9.81;
        k = 1;
        mu = 0.05;
        mum = 0.2;
        J = 100;
        gnum1 = [m*g];
        gden1 = [m mu mum];
        gnum2 = [k];
        gden2 = [J 0 0];
        numK=[kd kp];
        denK=1;
        [gnum3,gden3]=series(gnum1,gden1,gnum2,gden2);
        [gnum4,gden4]=series(gnum3,gden3,numK,denK);
        [numcl,dencl]=feedback(gnum4,gden4,1,1,-1);
        sys = tf(dencl, numcl)
        rlocus(sys);
        hold on
        pause(0.5)
    end
end

Error using tfchk
Transfer function not proper.

Error in series (line 66)
[num2,den2] = tfchk(c1,d1);

Answer 1

[cdawg]

This is happening because your numerator numK has more degrees than your denominator denK, making it not proper. I think you may have these variables switched. You can also check if your system is proper by using isproper.

Also, I'm not sure if you're doing this on purpose, but tf takes the inputs tf(numerator, denominator). Right now, you have tf(den,num).