Error in fprintf function

I have this line of code and it keeps saying there is an error using fprintf. I am trying to save data as a .dat file and every time I hit save this pops up. Can anyone help me understand why this is happening?

% save variable as text
    fid = fopen(save_name,'w');
    for i = 1:size(save_data,1);
        fprintf(fid,'%15d%15.3f%15.3f%15.6f%15.6f\n',...
             save_data(i,1), save_data(i,2), save_data(i,3),...
             save_data(i,4), save_data(i,5));
    end
    fclose(fid);

[Steven Lord]

Show us the full and exact text of the error message you receive (all the text displayed in red) and we may be able to determine what's causing it and how to modify your code so it no longer throws that error.

If my suspicion is correct you should also show us the size and class of the variable named save_data.

Answer 1

[per isakson]

"Invalid file identifier. Use fopen to generate a valid file identifier". The problem is most likely with this line

fid = fopen(save_name,'w');

Replace the fopen-line by

[fid,msg] = fopen(save_name,'w');
assert( fid >= 3, 'abc:def', 'Cannot open/create %s. Message: %s', save_name, msg ) 

and try to run the thus modified script of your question

[jonathan lochner]

Unfortunately, this did not help, but thank you for trying!

[per isakson]

The first measure when getting the message, "Invalid file identifier. Use fopen to generate a valid file identifier", is to verify that fopen returns a valid file identifier.

Did my two lines output an error message? And what did it say?

[per isakson]

You don't answer the questions of my previous comment. Thus, I guess that the problem of your original question is solved.

Now you introduce a new problem together with a dump of 809 lines of code (including comments). I assume, I cannot run this code because vital code is missing.

As far as I can see your first error messages

Error: File: saveResults.m Line: 356 Column: 9
Illegal use of reserved keyword "case".

is not thrown by code of the dump.

See:

• TUTORIAL: how to ask a question (on Answers) and get a fast answer
• Debug a MATLAB Program and Examine Values While Debugging

[Stephen23]

@jonathan lochner: please stop pasting 1000 lines of code and making the thread totally unreadable. You can simply upload the code by clicking the paperclip button (which is what I did for you today, and you can do in future).