data structure for simulation

[Francesco Potorti`]

I want to run a simulation on several inputs.  I can easily number each
input from 1 to 262143.  For each input, I have an output made of a
struct, like this:

octave> rss18(262143)
ans =
{
  tplemap =
     1   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1
  samples =  10
  qlev =
     0.50000   0.70000   0.75000   0.80000   0.90000
  qval =
     0.14278   1.39793   2.57294   2.93048   3.87450
  qerr =
     0.14338   1.48273   1.64111   1.69764       Inf
}

Where rss18 is a struct array whose only non-empty element is currently
the last one:

octave> whos rss18
Variables in the current scope:

  Attr Name        Size                     Bytes  Class
  ==== ====        ====                     =====  ===== 
       rss18       1x262143                   146  struct

Total is 262143 elements using 146 bytes

Now I would like to exploit a cluster of nodes by running several Octave
instances in parallel, each computing a subset of the 1:262143 space. (I
do not need anything more sophisticated.)  In the end, each of the
running Octaves would create its own struct array, which will be
partially empty.

I cannot find an efficient way of:
- finding which array elements are nonempty
- merging arrays with different sets of nonempty elements

Maybe struct arrays are not the best data structure for this purpose?

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