@Axel Vogt 

Actually it seems that is the option "Extended" in Typesetting/level that makes the difference.

The reults of the test you proposed is

convert(A, list);
[a, c, b, d]
convert(A, listlist);
[[1, 0], [0, 1]]

@acer  @Axel Vogt  @Carl Love

I erased the .maple* directories in my home directory and now the command prints correctly on the screen.

I am not familar with the "print/rtable" evaluation and I am still puzzled. If I set the display output option to

"Maple notation" here is what I get. This seems to say that the rtable in Matrix is not fully evaluated.  

restart; A := Matrix([[a, b], [c, d]]); a := 1; b := 0; c := 0; d := 1; A;
A := Matrix(2, 2, {(1, 1) = a, (1, 2) = b, (2, 1) = c, (2, 2) = d}, datatype = anything, storage = rectangular, order = Fortran_order, shape = [])
a := 1
b := 0
c := 0
d := 1
Matrix(2, 2, {(1, 1) = a, (1, 2) = b, (2, 1) = c, (2, 2) = d}, datatype = anything, storage = rectangular, order = Fortran_order, shape = [])

@Carl Love


I get the matrix

1 0

0 1

as I should 

@acer 

My bversion is 16.00 (debian testing intel32). 

I think it's a problem of rendering in the woorksheet: the worksheet "prints" on the screen exactly what I wrote (I tested it again Sreenshot.pdf )

But here is what I get if I make a brutal copy and paste from the worksheet in the Screenshot above into this page! You notice that a b c d have been replaced by their values! 

> A := Matrix([[a, b], [c, d]]); a := 1; b := 0; c := 0; d := 1; A;
print(`output redirected...`); # input placeholder
[a b]
A := [ ]
[c d]
a := 1
b := 0
c := 0
d := 1
[1 0]
[ ]
[0 1]

@Axel Vogt 

I have Maple 16.00. Is it possible that the the different behaviour depends on the avalaible memory?