how to get transfer function for this problem?

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I am working on following .m file.
n1=1;d1=1;
n2=1;d2=[1 1];
n3=1;d3=[1 2];
n4=1;d4=[1 3];
n5=4;d5=1;
n6=8;d6=1;
n7=12;d7=1;
nblocks=7;
blkbuild
q=[2 1 -5 0 0;3 2 -6 0 0 ;4 2 -6 3 -7;5 3 0 0 0;6 3 0 0 0;7 4 0 0 0];
input=1; output=4;
[A, B, C, D]=connect(a,b,c,d,q,input,output);
[num,den]=ss2tf(A,B,C,D);
printsys(num,den,'s')
when I get the answer it looks like this:
num/den =
1.0658e-014 s^2 + 1 s + 3
--------------------------
s^3 + 26 s^2 + 179 s + 210
BUT I WANT IT TO LOOK LIKE THIS, HOW CAN I DO IT. THANKS.
num/den =
1 s + 3
--------------------------
s^3 + 26 s^2 + 179 s + 210

Accepted Answer

Azzi Abdelmalek
Azzi Abdelmalek on 11 Oct 2012
you have just to remove the first coefficient from num
num=num(2:end)
model1=tf(num,den)

More Answers (1)

Udita Singh
Udita Singh on 9 Feb 2021
Edited: Walter Roberson on 9 Feb 2021
blkbuild command is showing an error
how can i resolve this??
close all;
clear all;
n1=1; d1=1;
n2=1; d2=[1 1];
n3=1; d3=[1 2];
n4=1; d4=[1,3];
n5=4; d5=1;
n6=8; d6=1;
n7=12; d7=1;
input=1;
output=4;
nblocks=7;
blkbuild;
q=[2 1 -5 0 0
3 2 -6 0 0
4 3 -7 2 -6
5 3 0 0 0
6 3 0 0 0
7 4 0 0 0];
[aa,bb,cc,dd]=connect(a,b,c,d,q,input,output);
[n,d]=ss2tf(aa,bb,cc,dd);
printsys(n,d,'s')
  2 Comments
Walter Roberson
Walter Roberson on 9 Feb 2021
What error are you observing? It seems to execute without difficulty.
n1=1; d1=1;
n2=1; d2=[1 1];
n3=1; d3=[1 2];
n4=1; d4=[1,3];
n5=4; d5=1;
n6=8; d6=1;
n7=12; d7=1;
input=1;
output=4;
nblocks=7;
blkbuild;
State model [a,b,c,d] of the block diagram has 7 inputs and 7 outputs.
q=[2 1 -5 0 0
3 2 -6 0 0
4 3 -7 2 -6
5 3 0 0 0
6 3 0 0 0
7 4 0 0 0];
[aa,bb,cc,dd]=connect(a,b,c,d,q,input,output);
[n,d]=ss2tf(aa,bb,cc,dd);
printsys(n,d,'s')
num/den = s + 3 -------------------------- s^3 + 26 s^2 + 179 s + 210
Udita Singh
Udita Singh on 9 Feb 2021
Edited: Udita Singh on 9 Feb 2021
Actually its not its showing me error
can you pls help me because its working perfectly in online matlab

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