Problem of SOS matrix to Transfer Function in IIR Filter Design using Matlab

Hi, everyone, I have to design a IIR filter using FDATOOL in Matlab.
And I expert it to workspace as SOS Matrix(SOS) and Scale Values(G).
Then I use function [b,a] = sos2tf(SOS,G) to acquire the Transfer
Function. However, it always report error:
>> [b,a]=sos2tf(SOS,G)
??? Error using ==> times
Matrix dimensions must agree.

Error in ==> sos2tf at 52
b = b.*g;

I don't know how to handle this problem, someone help me please.
Thanks a lot!

P.S. I just want to implement an IIF filter using C program language.
So I want to acquire the Transfer Function and then the difference
equation. And besides, if there is another way, please tell me. Thanks.

On Fri, 05 Jan 2007 01:58:41 -0000, X.Y. <Xieyu1219@gmail.com> wrote:

> Hi, everyone, I have to design a IIR filter using FDATOOL in Matlab.
> And I expert it to workspace as SOS Matrix(SOS) and Scale Values(G).
> Then I use function [b,a] =3D sos2tf(SOS,G) to acquire the Transfer
> Function. However, it always report error:
>>> [b,a]=3Dsos2tf(SOS,G)
> ??? Error using =3D=3D> times
> Matrix dimensions must agree.
>
> Error in =3D=3D> sos2tf at 52
> b =3D b.*g;
>

G must be a scalar value.



-- =

Oli

"Oli Charlesworth =D0=B4=B5=C0=A3=BA
"
> On Fri, 05 Jan 2007 01:58:41 -0000, X.Y. <Xieyu1219@gmail.com> wrote:
>
> > Hi, everyone, I have to design a IIR filter using FDATOOL in Matlab.
> > And I expert it to workspace as SOS Matrix(SOS) and Scale Values(G).
> > Then I use function [b,a] =3D sos2tf(SOS,G) to acquire the Transfer
> > Function. However, it always report error:
> >>> [b,a]=3Dsos2tf(SOS,G)
> > ??? Error using =3D=3D> times
> > Matrix dimensions must agree.
> >
> > Error in =3D=3D> sos2tf at 52
> > b =3D b.*g;
> >
>
> G must be a scalar value.
>
>
>
> --
> Oli

yes=A3=ACG is a scale value and it is given by FDATOOL, I have not changed
it.

On Jan 5, 12:48 pm, "X.Y." <Xieyu1...@gmail.com> wrote:
> "Oli Charlesworth =E5=86=99=E9=81=93=EF=BC=9A
> "
> > On Fri, 05 Jan 2007 01:58:41 -0000, X.Y. <Xieyu1...@gmail.com> wrote:
>
> > > Hi, everyone, I have to design a IIR filter using FDATOOL in Matlab.
> > > And I expert it to workspace as SOS Matrix(SOS) and Scale Values(G).
> > > Then I use function [b,a] =3D sos2tf(SOS,G) to acquire the Transfer
> > > Function. However, it always report error:
> > >>> [b,a]=3Dsos2tf(SOS,G)
> > > ??? Error using =3D=3D> times
> > > Matrix dimensions must agree.
>
> > > Error in =3D=3D> sos2tf at 52
> > > b =3D b.*g;
>
> > G must be a scalar value.
>
> > Oliyes=EF=BC=8CG is a scale value and it is given by FDATOOL, I have no=
t changed it

No, "scalar", as in "not a matrix or vector", i.e. a 1x1 variable.

--=20
Oli