defining arrays of structure

In order to increase the speed of processing, I am trying to define an array of structures before proceeding to my main code, say, 100×50 arrays of the same structure. How can I define it beforehand?

struct('dir1',{},'dir2',{},'x1',{},'x2',{},'x3',{},'x4',{})

is the following correct?

n1=100;
n2=50;
data{n1,n2}=struct('dir1',{},'dir2',{},'x1',{},'x2',{},'x3',{},'x4',{})

Thanks a lot for your quick reply :)

Answer 1

[Jan]

C = cell(100, 50);
S = struct('dir1', C, 'dir2', C ,'x1', C, 'x2', C, 'x3', C, 'x4', C);

Another method:

% S must be undefined before, otherwise use "clear('S')"
S(100, 50) = struct('dir1', [], 'dir2', [] ,'x1', [], ...
                    'x2', [], 'x3', [], 'x4', []);

[Walter Roberson]

You were faster this time, Jan!

Small typo, though: should be S(100, 50) instead of S(100. 50)

[AP]

then how do you call S referring to the element say for example (12,13)?

[AP]

that was reaaaaaaaaaaaaaaaaaaaly quick. :)))))

[Jan]

@Ahmad: S(12, 13) is corresponding struct. E.g. S(12, 13).dir1 = 'asd'.

@Walter: Ha, fast! I admit I've applied a trick: I've created an empty default answer, such that I have to insert just the needed characters.

[AP]

which of the two methods is more efficient in MATLAB?

[Jan]

@Ahmad: The S(100, 50)=struct() is 3 times faster. But we are talking about 0.1e-3 sec. I assume that reading this message will waste more time than using the worse method.

[AP]

Jan you're a real MATLABer :)

Thank you for your helps.