saving variables contained within a function

I need to save variables that are computed inside a function (called from a header) without providing them as output parameters. I can't use 'save' because the function is called inside a loop and it overwrites (the variables computed change over time). Is the only way to accomplish this through 'fprintf'?

Answer 1

[Rick Rosson]

It is probably not the only way to accomplish this task, but it will certainly work.

You can use fprintf to print to a text file instead of to the command window. Please check the documentation:

doc fopen
doc fclose
doc fprintf

The code would be something like:

filename = 'data.txt'; 
txt = fopen(filename,'w')
...
...
for ...
  ...
  fprintf(txt, '...\n' , ...);
  ...
end
...
...

fclose(txt);

...
...

HTH.

Rick

Answer 2

[Matt Fig]

Have you looked into the -append option of SAVE?

[Kyle Stanhouse]

yes but as i understand i would have to create a new name for the variable each time the function is called....the help documentation for save using append has this:

Note Saving with the -append option does not append additional elements to any arrays that are already saved in the MAT-file.

so if i went this route i would have to create a new name each time right?

Answer 3

[Rick Rosson]

Another approach would be to declare a persistent variable that will accumulate the results each time you call the function, and then perhaps write the results out to a MAT file the last time you call the function.

Please check the documentation:

   doc persistent

The function template would be:

   function y = foo(x)

      persistent results

      if isempty(results)
          results = zeros(...);
      end

      ...
      ...

   end

HTH.