Structure declaration in Matlab

Hello, I have a matlab code piece having a structure defined. I want to define the structure wrap around to assign these data. The code is as below.

estruct.func_name = 'DATA_1';

estruct.variable(1).name = 't_user';
estruct.variable(1).req_dim = [901 2];
estruct.variable(1).var = data1;
estruct.variable(1).type = 'USR1';

estruct.variable(2).name = 'x_user';
estruct.variable(2).req_dim = [901 3; 901 4; 901 5; 1 3; 1 4; 1 5];
estruct.variable(2).var = data2;
estruct.variable(2).type = 'USR2';

: :

estruct.variable(10).name = 'p_user';
estruct.variable(10).req_dim = [1 4; 1 5];
estruct.variable(10).var = data10;
estruct.variable(10).type = 'USR10';

All i want is define a structure to accept/store this data. Can anyone help me out please

Srikanth

[Jan]

What's wrong with the existing code?

[Srikanth]

Sorry i forgot to mention that i am trying out MATLAB Coder in MATLAB R2011a. When i include the above code, i get a error : Undefined function or variable 'estruct'. The first assignment to a local variable determines its class.

I feel i need to define the structure before assigning the data. Your comments please.

Regards Srikanth

Answer 1

[Friedrich]

Hi,

I dont have a MATLAB for testing at the moment but I guess the declaration should look like this:

estruct = struct('variable',{repmat(struct('name',[],'req_dim',[],'var',[],'type',[]),10,1)},'func_name','DATA_1')

I am not sure if the ML Coder likes repmat. If you get an error due repmat simply copy and past the inner struct definition 10 times.

Answer 2

[Srikanth]

Thanks for the reply. When i tried the above command, it gave an error - Cell arrays are not supported for code generation. How to solve this error ?

Thanks Srikanth

[Walter Roberson]

Leave out the { and } characters in the command Friedrich gave.

[Srikanth]

I tried this. The cmd i gave was :

estruct = struct('variable', ...

    struct('name',[],'req_dim',[],'var',[],'type',[]), ...
     struct('name',[],'req_dim',[],'var',[],'type',[]), ...
     'func_name','DATA_1');

I error it gave is :

Field and value input arguments must come in pairs.

"struct('variable', ..."

What do i do ?

Srikanth

Answer 3

[Srikanth]

Also, i tried only the following struct definition statement :

 estruct = struct('variable',repmat(struct('name',[],'req_dim',[],'var',[],'type',[]),10,1),'func_name','DATA_1')

With above line i was able to compile and generate code. But when i tried to assign data to the struct variables as below :

estruct.variable(1).name = 'x_time';
estruct.variable(1).req_dim = [901 6];
estruct.variable(1).var = x_time;

i get the error : Class mismatch (double ~= char). The class to the left is the class of the left-hand side of the assignment.

Function 'MATLAB Function' (#55.1056.1080), line 31, column 3: "estruct.variable(1).name"

How to solve this error ?

Thanks in advance Srikanth

[Friedrich]

Use ('name','') instead of []. When using[] ML assumes its double. Sorry, my fault

[Srikanth]

Thanks for the reply. The command now is :

 x_time = 9.0;

 estruct = struct('variable',repmat(struct('name','','req_dim',[], ...
    'var','','type',''),10,1),'func_name','DATA_1');

estruct.variable(1).name = 'x_time';
estruct.variable(1).req_dim = [901 6];
estruct.variable(1).var = x_time;

This gives a error :

Size mismatch (size [1 x 0] ~= size [1 x 6]).The size to the left is the size of the left-hand side of the assignment.

Function 'MATLAB Function' (#55.1079.1103), line 32, column 3: "estruct.variable(1).name"

If i give 6 spaces inside the '' (' '), the error shifts to the next variable - req_dim. How do i overcome this ?

Thanks Srikanth

[Friedrich]

Is name always of fixed size? If so do 'name',blanks(n), where n is the size.

If not fix, you need to make it of dynamically size:

http://www.mathworks.com/help/releases/R2012a/toolbox/eml/ug/bsvq5e4.html

[Srikanth]

Thanks it worked. I defined blanks and ones wherever required and it compiled.

Srikanth