Note that just after ‘filename2’ is opened, it is immediately closed:
fid = fopen(filename2, 'wt');
fclose(fid);
That could cause problems here:
%savedata
fprintf(fid, 'Reaction Time: %d', ReactionTime) ;
So even if ‘ReactionTime’ is defined and passed to the ‘savedata’ function as an argument (as it should be, rather than as a global variable), the function will throw this error:
Error using fprintf
Invalid file identifier. Use fopen to generate a valid file identifier.
I did that experiment to verify it.
For what it’s worth, I agree with others that global variables are not to be used. It is always possible to avoid using them by passing the variables as arguments to the functions using them.
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