In place function on a structure or a class

Hi,

I've encountered the following problem with in place editing. I have an in-place function, x = f(x). If I put x in a structure it is no longer in-place. Any ideas?

In-place:

function tmp
format debug
x = rand(1, 5);
x
x = cumsum(x);
x
end

/

>> tmp

x =

Structure address = 13e0854b0

m = 1

n = 5

pr = 60000f633020

0.1068    0.6538    0.4942    0.7791    0.7150
x =
Structure address = 13e11e5c0
m = 1
n = 5
pr = 60000f633020

0.1068    0.7605    1.2547    2.0337    2.7488

Not in-place:

function tmp
format debug
s.x = rand(1, 5);
s.x
s.x = cumsum(s.x);
s.x
end

/

>> tmp

ans =

Structure address = 13e11eda0
m = 1
n = 5
pr = 60000f633020

0.6099    0.6177    0.8594    0.8055    0.5767

ans =

Structure address = 13e11da60
m = 1
n = 5
pr = 60000b1ca5e0

0.6099    1.2275    2.0870    2.8925    3.4692

Answer 1

[Or Nahir]

I think this behavior is even more interesting. It seems as if a struct cannot free the pointer to an array. So once you assigned it a value, it would most likely be copied in the future.

In this example no copy is made:

function tmp
format debug
x= rand(1,5);
x
y = x;
y
clear y
x = x+1;
x
end

In this example x is copied in the line x = x+1, probably since clear s, didn't free the array.

function tmp
format debug
s.x = rand(1, 10);
x = s.x;
clear s
x
x = x+1;
x
end