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% given G1=1/(s+1), G2=1/s, G3=2
num1 = 1;
den1 = [1 1];
sysG1 = tf(num1,den1);
num2 = 1;
den2 = [1 0];
sysG2 = tf(num2,den2);
num3 = 2;
den3 = 1;
sysG3 = tf(num3,den3);
% series connection
sysG1G2 = sysG1*sysG2;
% unit feedback
numf = 1;
denf = 1;
sysF = tf(numf, denf);
% or sysG1G2F = feedback(sysG1G2,sysF,-1);
sysG1G2F = feedback(sysG1G2,sysF);
% parallel connection
[sysT] = parallel(sysG1G2F,sysG3)
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