Reference equality in Matlab struct. Can a struct have multiple field names pointing to the same object?

Question

If I have a struct in Matlab with multiple fields defined with the same object, would that be treated as one object in memory or recreated for each field? In other words, I would like to have multiple field names for one object, is that possible in Matlab?

For example,

function output = fn(input)

output = struct('field1',input,'field2',input)

end

Would output contain two copies of input or one?

Answer 1

I recently found out a way to find an answer. One can type in the followings in the Matlab cmd.

A=magic(3);
S=struct('field1',A,'field2',A);
format debug
S.field1
S.field2

The output for me was

>> S.field1

ans =


Structure address = 369610c0 
m = 3
n = 3
pr = 3fb54e40 
pi = 0
     8     1     6
     3     5     7
     4     9     2

>> S.field2

ans =


Structure address = 369610c0 
m = 3
n = 3
pr = 3fb54e40 
pi = 0
     8     1     6
     3     5     7
     4     9     2

Note that the pr values are the same for both fields.

I think pr is the pointer to the real part of the matrix. So since both fields share the same pointer, there is no duplication of the same object.