multiply each element of structured array, assignment of structured array

I'm not exactly sure if I'm using the right terminology. I have

A(1).B = 5; 
A(2).B = 6; 
A(3).B = 7;

>>A.B
ans =

      5

ans =

      6

ans =

      7

I have two questions: 1. I want to multiply each element of the structured array so that A.B*2 would equal 10,12,14 instead of 5,6,7. but instead I get the error

>>A.B*2
Error using  * 
Too many input arguments.

2. How do I make a copy of the structured array? I have tried but it just results in the first element.

>>C = A.B
C = 
      5

Likewise

>> C = A(1:3).B
C  =
      5

instead of C(1).B = 5, C(2).B = 6, and C(3).B = 7 like I want.

Answer 1

[per isakson]

The short answer is NO, it is not possible. However, ...

    >> [A.B] = split( 2*[A.B] )
    A = 
    1x3 struct array with fields:
        B
    >> A.B
    ans =
        10
    ans =
        12
    ans =
        14

where

    function  varargout = split( vec )
        assert( nargout == numel( vec )             ...
            ,   'split:narginNargoutMismatch'      ...     
         ,   'The number of outputs should match the length of the input vector.')
        varargout = num2cell( vec );
    end

Answer 2

[Jan]

C = [A(1:3).B];
% or C = [A(:).B]
% or C = [A.B]

This replies [5,6,7]. To get C(1).B = 5, C(2).B = 6, C(3).B = 7:

C = A;

A direct multiplication is not possible. Structs are simply not designed for arithmetic operations, because this can be done with numerical arrays much better. But it is possible with a loop:

F = fieldnames(A);
for iF = 1:length(F)
  aF = F{iF};
  A.(aF) = A.(aF) * 2;
end

[John Petersen]

In this case C is converted to an array. I want to be able to keep it a structured array.

I only want A.B to be copied and there are other fields associated with A that I don't want copied to C. thanks.

[Ella]

Hi! So I have a structure with a variable amount of entries. It will always be greater than 1. These stats (Area, MinFeret.. etc) need to be converted to mm. I tried to use the for loop approach, but it says there are too many inputs. Here is my code.

F= fieldnames(stats);

for iF = 1:length(F)

aF = F{iF};

stats.(aF) = stats.(aF) .* pixelSize;

end

Any advice for how I can make it work or another way to do this?