# extract num and den from matrix transfer function

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msh jgtu on 6 Aug 2020
Edited: madhan ravi on 6 Aug 2020
how to use numerator and denominator (N,D) of the output transfer function yv. where yv is 16 tranfer functions. i want to see N and D and use them in another process.
for i=1:4
for j=1:4
gvi(i,j)=tf(N(i,:),D(j,:))
yv(i,j)=series(yc,gvi(i,j))
end
end
[N,D]= tfdata(yv)%%%% this line doesn't show the content of N and D

madhan ravi on 6 Aug 2020
Edited: madhan ravi on 6 Aug 2020
Use it inside the loops, preallocation is recommended for the variables.

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madhan ravi on 6 Aug 2020
ctr = 0;
[gvi, yv, N, D] = deal(cell(4*4, 1));
for ii = 1 : 4
for jj = 1 : 4
ctr = ctr + 1;
gvi{ctr} = tf(N(ii,:),D(jj,:))
yv{ctr} = series(yc, gvi{ctr})
[N{ctr}, D{ctr}]= tfdata(yv)
end
end
celldisp(N)
celldisp(D)
msh jgtu on 6 Aug 2020
error
Error using tf (line 287)
The values of the "num" and "den" properties must be row vectors or cell arrays of row vectors, where each
vector is nonempty and containing numeric data. Type "help tf.num" or "help tf.den" for more information.
Error in forloop (line 60)
gvi{ctr} = tf(N(ii,:),D(jj,:))
madhan ravi on 6 Aug 2020
Without knowing the missing variables , can’t help further.