Creating a binary file using fwrite

Hello

I'm wondering if anyone can help me. I don't have any experience creating binary files or doing what I need to do so this might be a silly question :)

I have a 3D matrix, 24x10x24 (time X layers X nodes). I'm trying to write a for loop for that it runs through the 10 layers with both time and nodes being 1, then I need it to run through each each layer with time being 1 and nodes being 2, and so on for each node. e.g

% [Double] U(1,1,1)
% [Double] V(1,1,1)
% ...[Double] U(nLayers,1,1)
% [Double] V(nLayers,1,1)
% [Double] U(1,2,1)
% [Double] V(1,2,1)
% ...[Double] U(nLayers,2,1)
% [Double] V(nLayers,2,1)
% ... ... ...[Double] U(nLayers,nNodes,1)
% [Double] V(nLayers,nNodes,1)

% [Double] U(1,1,2)
% [Double] V(1,1,2)
% ...[Double] U(nLayers,1,2)
% [Double] V(nLayers,1,2)
% [Double] U(1,2,2)
% [Double] V(1,2,2)
% ...[Double] U(nLayers,2,2)
% [Double] V(nLayers,2,2)
% ... ... ...[Double] U(nLayers,nNodes,2)
%   [Double] V(nLayers,nNodes,2)

I've written some code, but I don't think its right at all since I can't really wrap my head around what I need to do anyway. And I probably haven't explained myself very well. If anyone has any ideas, I would really welcome them :)

Code so far (very wrong):

for lp=1:length(nLayers);
    fwrite(fileID,FV.u(1,lp,1),'double','ieee-be');
    fwrite(fileID,FV.v(1,lp,1),'double','ieee-be');
    for lq=1:length(nNodes);
    fwrite(fileID,FV.u(1,lp,lq),'double','ieee-be');
    fwrite(fileID,FV.v(1,lp,lq),'double','ieee-be');
    for lt=1:length(nTimeStep);
        fwrite(fileID,FV.u(lt,lp,lq),'double','ieee-be');
        fwrite(fileID,FV.v(lt,lt,lp),'double','ieee-be');
    end
end

Answer 1

[Walter Roberson]

Your code writes u(1,lp,1) and then writes it again as the first element of u(1,lp,lq)

[Meghan]

I know, that's why I've said my code is very wrong.

I need it to run through each element in lp for every element in lq. I just don't think my code does that. And because I'm creating a binary file, I can't check to see if it actually works properly.

[Walter Roberson]

Use permute() so that the data is ordered with the data to be written first runs along the first column, then the second, to end of first layer, then along first column of next layer and so on. Now reshape to a row vector. Do the same for v including reshape to a row vector. vertcat the two row vectors u above v. Now fwrite the result all as a single call.

[Walter Roberson]

If you are using Linux or OS X then you can use "od" to examine the contents of the binary file

[Meghan]

Sorry I realised that I'd already written the code and got the answer I wanted. I just had it a bit fuzzy. Never written anything to binary before so a little all over the place!

Thanks for the help anyway :)