how know size of field struct

hi,

Sis is a struct

D is a field of struct

size(Sis.D)

>> size(Sis.D)

Error using size

Answer 1

[Walter Roberson]

What you failed to indicate is that Sis is a non-scalar struct. Sis.D is then "struct expansion". So

size(Sis.D)

is the same as if you had written

size(Sis(1).D, Sis(2).D, Sis(3).D, Sis(4).D, up to Sis(63).D))   %or whatever the size of Sis is

You can inquire about size(Sis(1).D) or size(Sis(end).D) or as appropriate.

If you need to know the size of each of the Sis.D entries then

SisSizes = arrayfun(@(S) size(S.D), Sis, 'uniform', 0);

If all of the Sis.D entries had the same dimension then you could also proceed to

SisSizeArray = cell2mat(SisSizes(:));

which would be a numeric array with numel(Sis) rows and numdim(Sis(1).D) columns

Answer 2

[the cyclist]

That command will give an error for some values of Sis.D, and not for others. Regardless, I don't think it will do what you expect. For example, what do you think size(Sis.D) should give for the following struct?

Sis(1).D = [1 2];
Sis(2).D = [1 2 3];
Sis(3).D = [1; 2; 3];

Perhaps you should upload your data, and explain what you are trying to do.

[piero]

ok ..i understand

the .D have same length in all field in struct