inputting an output file name into a function

HI,

I have a function:

function=tcaproc(mults,c2flag,filename)

where I do some math and then want to print to a file called filename.txt, for example, something like data1out.txt. I want to be able to change the filename is my point. So far I have tasted only abject failure.

formatSpec='%s.txt';
str=sprintf(formatSpec,filename)
file=fopen(str,'wt+');

just tells me that my filename doesn't exist.

test=tcaproc(as4,1,test1);
Undefined function or variable 'test1'.

I would appreciate your help.

Answer 1

[Image Analyst]

When you do this:

file=fopen(str,'wt+');

you're getting an ID number (a "handle") to the file. So you'd do this:

function tcaproc(mults,c2flag,filename)
try
  formatSpec='%s.txt';
  baseFileName = sprintf(formatSpec, filename)
  fullFileName = fullfile(pwd, baseFileName);
  fileHandle= fopen(fullFileName ,'wt+');
  % More code...... such as fprintf(fileHandle, '%s', someText);

% Handle any errors:
catch ME
    errorMessage = sprintf('Error in function tcaproc.\n\nError Message:\n%s', ME.message);
    fprintf(1,'%s\n', errorMessage);
    uiwait(warndlg(errorMessage));
  end

And you'd call it like this:

filenameInMainProgram = 'test';
tcaproc(multsInMainProgram, c2flagInMainProgram, filenameInMainProgram);

Answer 2

[Walter Roberson]

test=tcaproc(as4,1,'test1');

[Matthew]

It was not quite that simple, but it was very close. The marked answer below was right on the money. THANKS TO ALL.