If the output format changed, it wasn't intentional.

I agree that each element of a struct or cell should be formatted independently of context.  I really don't want to have the function that displays the contents of a matrix checking to see whether it is called in the context of displaying a cell or struct or some other object and doing special things because of that.

Meta comment:  I find it a little crazy that people seem to care about this issue and expect that Octave displays all output exactly as Matlab does.  But whatever, we could certainly have an option.  Or, now it should be possible for you to write your own @cell/display.m and @cell/disp.m functions to do whatever you want.

Thanks for checking in Matlab.  Should we make it a goal of Octave to move to the Matlab method of displaying cell arrays?  Or is what we have good enough?

There are a number of differences in the display of variables between Matlab and Octave related to the compact/loose option to format.

The first, which I don't think we should change, is the the universal presence of a newline after the name of the variable in Matlab.  Under Octave, the interpreter makes a decision about how large the display of the variable will be and if it is short, it puts it all on one line.  I like that.

For instructional purposes, here are the documented Matlab display of the same variable under compact/loose

Compact:
theta = pi/2
theta =
  1.5708

and

Loose:
theta = pi/2

theta =

  1.5708

Under Octave with either format

theta = pi/2
theta =  1.5708

The question is how to display something more complicated, like a matrix, under the two different formats.  This is the result under 4.2.0

>> x = magic (3);
>> format compact
>> x
x =
   8   1   6
   3   5   7
   4   9   2
>> format loose
>> x
x =

   8   1   6
   3   5   7
   4   9   2

>>

The difference is a newline before and after the matrix.  However, there is no newline before the name of the variable "x =" as there is in Matlab under format loose to help separate the interpreter command from the display.  Maybe that is worth changing?

A second possible change is that the newline is always inserted after the matrix object, when for cells it should be after the cell braces which mark the start and end of the object.

An example is

>> format compact
>> y = {magic(2); magic(3)}
y =
{
  [1,1] =
     4   3
     1   2
  [2,1] =
     8   1   6
     3   5   7
     4   9   2
}
>> format loose
>> y
y =
{
  [1,1] =

     4   3
     1   2

  [2,1] =

     8   1   6
     3   5   7
     4   9   2

}
>>

Again, just a question, but maybe it would make more sense to remove the newline before the final '}' and place it after the '}' so there was some space before the start of the next interpreter command prompt.  Someone could also check under Matlab and see how it treats these examples.