NEED HELP! In an assignment A(:) = B, the number of elements in A and B must be the same.

I have to do a method which saves on an array some hash results from a SHA-384 function. That's what I'm using: http://www.mathworks.com/matlabcentral/fileexchange/31272-datahash

I need to save the results on an array 'cause then I need to use it as an input on another function.

That's what I do:

    clear
  N=1000;
  a=zeros(1,N);

Opt = struct('Format', 'HEX', 'Method', 'SHA-384' ,'Input', 'array');
for k=1:N

    a(k)=DataHash(k, Opt);

end

And that's the error:

In an assignment A(:) = B, the number of elements in A and B must be the same.

Error in Untitled2 (line 8) a(k)=DataHash(k, Opt);

If I don't save the results from the function DataHash it works without any problem;

ans =

DE2B5CBB9F372EA7F5F3ABC7091D668ACF7B008FC0063BF068B3AAEC38B793A87B031874B838C4639A83FBC38AE95E7F

ans =

1F34BE5A6B2E8E1BA250A15793111A8AE7FEB7B891FDB28947F30A9A1047C0ED37CDC5C5B380C51743CEF536A4DF35C3

ans =

75A59F46AD758957780CF5485DDC17B3D13DC0175D21C519FB5F4E839DE79028C12C6E3FA5E41C8D08916A34EAFA6501

............

I have read some answers about the same ERROR but I couldn't fix it.

Could someone help me?

Thank's a lot.

BTW: Sorry for my english

Answer 1

[Thorsten]

 a(k,:)=DataHash(k, Opt);

[Pablo Fernandez Diaz]

I tried it but it still doesn't work:

clear
N=1000;
a=zeros(1,N);

Opt = struct('Format', 'HEX', 'Method', 'SHA-384' ,'Input', 'array');
for k=1:N

a(k,:)=DataHash(k, Opt);

end

But that's the error now:

    Subscripted assignment dimension mismatch.

        Error in Untitled2 (line 8)

Anyway thanks for the help

[Thorsten]

What does DataHash(k, Opt) return, precisely? What's the size, and does the size change depending on k?

Answer 2

[Jan]

You create a [1 x 1000] double array at first:

a = zeros(1,N);

Inside the loop you try to insert the data of a string with 96 characters:

a(k) = DataHash(k, Opt);

a(k) is a single element, and you cannot store 96 characters in a single element. In addition it is converted to a double, but this is not the problem here.

This cannot work also:

a(k, :) = DataHash(k, Opt);

a has 1000 elements per row due to zeros(1, 1000). Then a(k, :) is a vektor of 1000 elements and you cannot assign 96 characters to it.

Use a cell string instead:

N = 1000;
C = cell(1,N);
Opt = struct('Format', 'HEX', 'Method', 'SHA-384' ,'Input', 'array');
for k = 1:N
  C{k} = DataHash(k, Opt);   % Curly braces
end

[Pablo Fernandez Diaz]

IT WORKS!!!! Thank you so much!!

[Jan]

You are welcome.

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