Bug in Maple 9.5 "Svd" singular value decomposition code?

Greetings

Have a look at this input and output:

-----BEGIN INCLUDED MATERIAL-----
> restart:
> with(linalg):
> W := matrix(2,4,[1,0,0,0,0,0,0,1]);
> Diag := matrix(2,4,[0,0,0,0,0,0,0,0]):
> D1 := evalf(Svd(W, U, V));
> Diag[1,1] := D1[1]: Diag[2,2] := D1[2]:
> evalm(U); evalm(Diag); evalm(V);
> evalm(U &* Diag &* transpose(V));
Warning, the protected names norm and trace have been redefined and
unprotected
[1 0 0 0]
W := [ ]
[0 0 0 1]
D1 := [1., 0.]
[-1. 0.]
[ ]
[ 0. 1.]
[1. 0 0 0]
[ ]
[ 0 0. 0 0]
[-1. 0. 0. 0.]
[ ]
[ 0. 1. 0. 0.]
[ ]
[ 0. 0. 0. -1.]
[ ]
[ 0. 0. -1. 0.]
[1. 0. 0. 0.]
[ ]
[0. 0. 0. 0.]
-----END INCLUDED MATERIAL-----

The second entry in D1 is wrong - it should be 1. When I multiply back
out the matrices as U*Diag*transpose(V), I should get back what I
started with.

Note that if I use linalg[singularvals], it works fine:

-----BEGIN INCLUDED MATERIAL-----
> singularvals(W);
[1, 1]
-----END INCLUDED MATERIAL-----

Which is just as it should be.

Matlab gives:

-----BEGIN INCLUDED MATERIAL-----
>> W = [1 0 0 0 ;
0 0 0 1]

W =

1 0 0 0
0 0 0 1

>> [U D V] = svd(W)

U =

1 0
0 1


D =

1 0 0 0
0 1 0 0


V =

1 0 0 0
0 0 0 -1
0 0 1 0
0 1 0 0

>> U*D*V'

ans =

1 0 0 0
0 0 0 1

>>
-----END INCLUDED MATERIAL-----

which, again, is as it should be. So, is there a known bug in Maple
9.5's Svd code, or am I overlooking something? ;)

--
-Bo Parker

The email address in the header is fake.

.

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