transfer function multiplication and plotting

Question

aaa 2012-1-25

hi have some code that looks like

TF = tf(num,den,1/(60));
g1 = 10*TF;
f = iztrans(g1)

but when i do this, matlab returns

    ??? Undefined function or method 'iztrans' for input arguments of
type 'tf'.

is there a solution around this? can i make my transfer function not as a 1x1 tf and as a different format? this is very frustrating,

thanks for the helps.

Answer 1

Walter Roberson 2012-1-25

iztrans() is from the Symbolic Toolbox, and takes a symbolic expression. It is the inverse of the symbolic ztrans()

I am not sure what you are wanting to do, but if you are wanting to get the numerator and denominator of the new system, then you would use

[num,den,Ts] = tfdata(TF)

Or perhaps you want to inv(TF) ?