Hello,
Each time you use Add, it adds perm as a new list entry in out. It does NOT add
the current value of perm as a new list entry in out, but rather inserts a
reference to the list perm. The list perm is added to the list out three times,
and by the time the function returns, perm = [1,2,3], so out consists of three
[1,2,3].
If you want to remember previous states of a list, you'll always need to make a
copy, because this is not done automatically when using functions like Add. Try
using for example the ShallowCopy function.
Hope that helps.
Yours,
Keshav
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2011/1/8 Hebert Pérez-Rosés
<hebert.pe...@gmail.com<mailto:hebert.pe...@gmail.com>>
Dear all,
I'm embarrased to say this, but I'm very puzzled by the behaviour of the Add
function. I have this simple test code:
--------------------------------------
TestFun:= function(n)
local perm, out, i;
out:= [];
perm:= [];
for i in [1..n] do
perm[i]:=0;
od;
for i in [1..n] do
perm[i]:= i;
Add(out, perm);
od;
return out;
end;
----------------------------------
If I now make a call to Test(3), I should get [ [1,0,0], [1,2,0], [1,2,3] ],
right? However, I'm getting [ [1,2,3], [1,2,3], [1,2,3] ]. Do you get the
same thing? Can anybody explain to me what's happening here?
Thank you very much in advance,
Hebert Perez-Roses
The University of Newcastle, Australia
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