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access data read from file

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F ziegler
F ziegler on 27 Dec 2016
Answered: F ziegler on 2 Jan 2017
Trying to read a text file of real numbers into an array, then output the data sequentially as part of a matlab function in Simulink. Main problem is, if I don't initialize the array "RF=zeros(Filesize,1)" the "Output=RF(CountRom/2)" complains "Subscripting into an mxArray is not supported". Setting "Filesize" requires prior knowledge of the length of the file. If "Filesize" is wrong, the fscanf complains that the "read" and "expected" don't match. I'm sure there's a simple solution, just not sure what it is.
function Output = ReadTxt()
coder.extrinsic('fopen')
coder.extrinsic('fclose')
coder.extrinsic('fscanf')
FileSize = 29866;
persistent CountRom RF
if isempty(CountRom)
CountRom = uint32(0);
RF = zeros(FileSize,1);
fid = -1;
fid = fopen('Filename.txt', 'r');
if (fid > 0)
RF=fscanf(fid, '%f');
fclose(fid);
else
error('File open failed');
end
end
if (CountRom < FileSize)
CountRom = CountRom + 1;
Output = RF(CountRom / 2); % note, RF is base 1
else
fclose('all');
Output = 0;
end
end
  1 Comment
Walter Roberson
Walter Roberson on 27 Dec 2016
You might be able to get further with coder.varsize()

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Answers (2)

Prateek Khandelwal
Prateek Khandelwal on 2 Jan 2017
Have you considered using 'From File' block ? if your aim is to get data from the file at each time step, this might be the solution for you.
Here is the doc link: https://www.mathworks.com/help/matlab/ref/fscanf.html

F ziegler
F ziegler on 2 Jan 2017
I'm also capturing responses in the same script and both are relative to a mask parameter.

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