Re: Simple routine won't run.

[Przemek Klosowski]

   Have written a (very first) octave routine:
   ...
   
d^i*(1-d)^(1-i)*(d/2)^(k+j)*(1-d/2)^(2-k-j))*log(d^i*(1-d)^(1-i)*(d/2)^(k+j)*(1-d/2)^(2-k-j))
   ....
   
d^i*(1-d)(1-i)*(d/2)^j*(1-d/2)^(1-j))log(d^i*(1-d)(1-i)*(d/2)^j*(1-d/2)^(1-j))
   ....
   (d/2)^(k+j)*(1-d/2)^(2-k-j)log((d/2)^(k+j)*(1-d/2)^(2-k-j))

There are issues with your expressions; for instance, the second one misses
some operators. I think you meant 

   
d^i*(1-d)*(1-i)*(d/2)^j*(1-d/2)^(1-j))*log(d^i*(1-d)*(1-i)*(d/2)^j*(1-d/2)^(1-j))

I would recommend practicing with some simpler expressions and functions before
tackling your fairly complicated problem.

Here's a neat trick: it turns out that properly formed Octave's expressions 
are, most
of the time, also valid Maxima expressions, and Maxima can format them nicely::

    (%i6) 
(d^i*(1-d)*(1-i)*(d/2)^j*(1-d/2)^(1-j))*log(d^i*(1-d)*(1-i)*(d/2)^j*(1-d/2)^(1-j));
    (%o6)
                                                            d 1 - j  j + i
                                               (1 - d) (1 - -)      d      (1 - 
i)
                    d 1 - j  j + i                          2
       (1 - d) (1 - -)      d      (1 - i) 
log(-----------------------------------)
                    2                                           j
                                                               2
       
----------------------------------------------------------------------------
                                             j
                                            2

    (%i7) tex(%o6);
    $${{\left(1-d\right)\,\left(1-{{d}\over{2}}\right)^{1-j}\,d^{j+i}\,
     \left(1-i\right)\,\log \left({{\left(1-d\right)\,\left(1-{{d}\over{2
     }}\right)^{1-j}\,d^{j+i}\,\left(1-i\right)}\over{2^{j}}}\right)
     }\over{2^{j}}}\leqno{\tt (\%o6)}$$


so you can see if the expressions you are writing are indeed what you think
they are, and you can even cut and paste the TeX output and get a nice printout.

Maxima is conveniently packaged for major Linux distributions, so to
install it I just did 'yum install maxima-gui'; I would expect that
it's available as a Debian package as well---can y'all confirm that?


Note that in Octave you want to avoid explicit loops, and the above formula
for e.g. x21 can be written as 

  [i,j]=meshgrid(0:1,0:1);
  
x21=sum(sum((d.^i.*(1-d).*(1-i).*(d/2).^j*(1-d/2).^(1-j)).*log(d.^i.*(1-d).*(1-i).*(d/2).^j.*(1-d/2).^(1-j))))

For short loops like yours, it doesn't really matter that much, but this style
is even easier to debug because you can print out the result of the expression
that is the argument to sum(sum()), and you'll see all the operands.