Re: residue() confusion

[Henry F. Mollet]

The result for e should be [1 2 1 2] (multiplicity for both poles). Note
that Matlab does not even give e.  My mis-understanding of the problem was
pointed out by Doug Stewart. Doug posted new code yesterday, which I've
tried unsuccessfully, but I cannot be sure that I've implemented residual.m
correctly. The corrected code still produced e = [1 1 1 1] for me.
Henry


on 9/22/07 1:31 PM, Ben Abbott at address@hidden wrote:

> 
> As a result of reading through Hodel's
> http://www.nabble.com/bug-in-residue.m-tf4475396.html post  I decided to
> check to see how my Octave installation and my Matlab installation responded
> to the example
> 
> Using Matlab v7.3
> --------------------------
>  num = [1 0 1];
>  den = [1 0 18 0 81];
>  [a,p,k] = residue(num,den)
> 
> a =
> 
>         0 - 0.0926i
>    0.2222 - 0.0000i
>         0 + 0.0926i
>    0.2222 + 0.0000i
> 
> 
> p =
> 
>    0.0000 + 3.0000i
>    0.0000 + 3.0000i
>    0.0000 - 3.0000i
>    0.0000 - 3.0000i
> 
> 
> k =
> 
>      []
> --------------------------
> 
> Using Octave 2.9.13 (via Fink) on Mac OSX
> --------------------------
>  num = [1 0 1];
>  den = [1 0 18 0 81];
>  [a,p,k] = residue(num,den)
> 
> a =
> 
>   -3.0108e+06 - 1.9734e+06i
>   -3.0108e+06 + 1.9734e+06i
>   3.0108e+06 + 1.9734e+06i
>   3.0108e+06 - 1.9734e+06i
> 
> p =
> 
>   -0.0000 + 3.0000i
>   -0.0000 - 3.0000i
>    0.0000 + 3.0000i
>    0.0000 - 3.0000i
> 
> k = [](0x0)
> e =
> 
>    1
>    1
>    1
>    1
> --------------------------
> 
> These are different from both the result that
> http://www.nabble.com/bug-in-residue.m-tf4475396.html Hodel obtained , as
> well as different from
> http://www.nabble.com/bug-in-residue.m-tf4475396.html Mollet's
> 
> Thoughts anyone?
>