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# "??? Undefined function or variable" in a function (should be easy...?)

Asked by Max on 19 Jul 2013

Hi everyone,

I'm trying to write a function that will take a vector of results and summarize the data into several categories.

I'm having an issue that's really confusing me, here are the first few lines of my function:

```function summwriter(resultLogMain, subjectID)
```
```filename = strcat('Results/summData',subjectID,'.txt');
outfile = fopen(filename, 'wt');
```
```numberOfEntries = length(resultLogMain(1,:));
```
```cat1_ln = 0;
cat1_hn = 0;
cat1_rts = zeros(1, numberOfEntries);
```

then later I use a "for" loop to fill in some values:

```for i = 5:numberOfEntries;
%Faces have no influence
if resultLogMain(9,i) == 2 && resultLogMain(11,i) == 2;
cat1_rts(i) = resultLogMain(2,i);
%Subject chose hard task
if resultLogMain(1,i) == 1;
%12% win trial
if resultLogMain(12,i) == 0.12;
cat1_ln = cat1_ln + 1;
% 88% win trial
elseif resultLogMain(12,i) == 0.88;
cat1_hn = cat1_hn + 1;
end
end
end
end
```

and then calculate some percentages, averages, and standard deviations

```cat1_lp = cat1_ln/(numberOfEntries);
cat1_hp = cat1_hn/(numberOfEntries);
cat1_rtav = mean(cat1_rts(:));
cat1_rtsd = std(cat1_rts(:));
```

These excerpts cover one category, there are actually four but I think if I can figure it out for one I can understand the issue. Right now when I run the script it returns the error:

??? Undefined function or variable 'cat1_ln'.

Even though cat1_ln is CLEARLY defined right before the loop to be preallocated and filled in.

Am I doing something very simple very wrong? Does it have something to do with defining a new variable within a function? Any help would be great!

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Answer by per isakson on 19 Jul 2013

Set

`    >> dbstop if error  `

and inspect the Workspace window when the break occur

Here are some links on debugging in Matlab

Answer by Jan Simon on 19 Jul 2013

We see, that you define cat1_ln before the loop. I guess, that the error occurs inside the loop (this would have been cleared, if you post the complete error message, which contains the crashing line). Then it is obvious, that you either have a typo in the code (1 and l looks so similar) or that the already defined variable is removed by a clear.

Does "then later" contain calls of scripts, which use clear all?

Answer by Image Analyst on 19 Jul 2013

Put "workspace" at the beginning of your code

workspace; % Show workspace panel.

to show the workspace panel of variable (if it's not already showing). Then set a breakpoint and step line by line (F10 key) until you see cat1_ln appear, then disappear. Like Jan says - it probably disappears when you execute a clear.