scheme-question: matrix-operation

[Thomas Morley]

Hi,

lets say I've a list of sublists like '((1 2 3)(4 5 6))
I want to modify it, the result should be '((1 3 5)(2 4 6))

This is a matrix-operation (not sure whether matrix is the correct
english term), on could write it graphically:
1 2 3
4 5 6
->
1 3 5
2 4 6

What's the best scheme-way to get it?

All but the last sublist will be of equal lengths, the last may or may
not be shorter.

Thanks,
  Harm