problem with residue and repeated complex roots

[Doug Stewart]

I am running qtoctave on windows XP octave version 2.9.15
residue doesn't give the correct answer for repeated complex roots

her is Matlab's result

» n
n =
    1
» d
d =
    1     8    42   104   169
» roots(d)
ans =
 -2.0000+ 3.0000i
 -2.0000- 3.0000i
 -2.0000+ 3.0000i
 -2.0000- 3.0000i
» [a b c]=residue(n,d)
a =
 1.0e+005 *
  1.2662+ 1.8232i
  1.2662- 1.8232i
 -1.2662- 1.8232i
 -1.2662+ 1.8232i
b =
 -2.0000+ 3.0000i
 -2.0000- 3.0000i
 -2.0000+ 3.0000i
 -2.0000- 3.0000i
c =
    []

and qtoctave's results

> > n

n = 1

> > d

d =

1 8 42 104 169

> > roots(d)

ans =

-2.0000 + 3.0000i

-2.0000 - 3.0000i

-2.0000 + 3.0000i

-2.0000 - 3.0000i

> > [a b c]=residue(n,d)

a =

-9.3613e-018 - 9.2593e-003i

-2.7778e-002 - 5.3894e-010i

2.3130e-018 + 9.2593e-003i

-2.7778e-002 + 5.3894e-010i

b =

-2.0000 + 3.0000i

-2.0000 + 3.0000i

-2.0000 - 3.0000i

-2.0000 - 3.0000i

c = [](0x0)



I haven't looked into why this is happening yet.

Doug Stewart