BRMLtoolbox pot() function not defined.

I am working with the BRMLtoolbox for MATLAB. You can download it in the link provided and just run setup.m file.

This is the structure of the BRMLtoolbox:

I was trying to work with one of the Demo Exercises, as described in the book Bayesian Reasoning and Machine Learning at page 35 of the pdf. For simplicity, I've taken a screenshot of the page:

Now, you don't need to know anything about the underlying mathematics to help me solve this issue. I am new to MATLAB (started learning it today, coming from Python). I started going through the demoClouseau.m file contained in the DemosExercises folder. This is what it looks like:

      function demoClouseau
      %DEMOCLOUSEAU inspector clouseau example

      import brml.*

      butler=3; maid=2; knife=1; % Variable order is arbitary
      murderer=1; notmurderer=2; used=1; notused=2; % define states, starting from 1.

      % The following definitions of variable are not necessary for computation,
      % but are useful for displaying table entries:
      variable(butler).name='butler'; variable(butler).domain = {'murderer','not murderer'};
      variable(maid).name='maid'; variable(maid).domain ={'murderer','not murderer'};
      variable(knife).name='knife'; variable(knife).domain={'used','not used'};

      % Three potential since p(butler,maid,knife)=p(knife|butler,maid)p(butler)p(maid).
      % potential numbering is arbitary

      pot(butler)=array;
      pot(butler).variables=butler;
      pot(butler).table(murderer)=0.6;
      pot(butler).table(notmurderer)=0.4;

      pot(maid)=array;
      pot(maid).variables=maid;
      pot(maid).table(murderer)=0.2;
      pot(maid).table(notmurderer)=0.8;

      pot(knife)=array;
      pot(knife).variables=[knife,butler,maid]; % define array below using this variable order
      pot(knife).table(used, notmurderer, notmurderer)=0.3;  
      pot(knife).table(used, notmurderer, murderer)   =0.2;
      pot(knife).table(used, murderer,    notmurderer)=0.6;
      pot(knife).table(used, murderer,    murderer)   =0.1;
      pot(knife).table(notused,:,:)=1-pot(knife).table(used,:,:); % due to normalisation

      jointpot = multpots(pot); % joint distribution

      drawNet(dag(pot),variable);
      disp('p(butler|knife=used):')
      disptable(condpot(setpot(jointpot,knife,used),butler),variable);

Now, I can run this script no problem and this is the output of it:

And this is the plot that comes out:

So it seems to be running no problem! However, if I just use the command line and type

    import brml.*
    pot(1)

As suggested in the book, I get an error! `Undefined function or variable 'pot'.` What is pot? Is it a variable? Is it a function? Is it a class? I thought it was a class defined in the BRMLtoolbox, but I cannot find it.

I tried debugging the code by putting a breakpoint as such:

And there are some weird things happening:

• First of all, the code did not break, I did not get the error above.
• Secondly, if Now I write `pot` in the Console, I get an answer!

So somehow, pot here works, although it is not defined in the code!

What is going on? I cannot even understand the syntax, it seems to kind of define `pot` on the fly with the pot(butler) = array statement, but I can't quite figure it out.

Answer 1

[Vyas Raina]

Hey, don't know if this is relevant anymore to you, but it may be useful for other viewers:

"pot" has nothing to do with the BRML toolkit. You could have very well done blob(X) = array; It is just another way of defining an object in matlab that takes X as an argument...

For others also interested in the Clouseau Problem, there is a good explanation at:

https://www.youtube.com/watch?v=x6T4fgClbGk