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<div class="moz-cite-prefix">Paul,<br>
<br>
There is an option (which was meant for debugging) in Clp which
gives statistics on a problem - and with some obscure options can
write out decomposed matrices as individual mps files.<br>
<br>
However your model, as formulated, does not totally decompose into
blocks. The model you sent me has 6 blocks and we get -<br>
<br>
3 master rows 1152 <= < 1155<br>
**Useful 6 blocks (largest 192,456), 3 master rows (0 empty) out
of 1155, 3 master columns (0 empty, 0 integer) out of 2739<br>
Block 0 has 192 rows and 456 columns (920 elements, 88 integers)<br>
Block 1 has 192 rows and 456 columns (920 elements, 88 integers)<br>
Block 2 has 192 rows and 456 columns (920 elements, 88 integers)<br>
Block 3 has 192 rows and 456 columns (920 elements, 88 integers)<br>
Block 4 has 192 rows and 456 columns (920 elements, 88 integers)<br>
Block 5 has 192 rows and 456 columns (920 elements, 88 integers)<br>
<br>
So there remain 3 variables and rows. Each row has entries in all
six blocks and so we can't go any further.<br>
<br>
The 3 variables are just there to report on the objective values.
If we move those row entries to objective and get rid of the
variables and rows, then the problem does decompose and the 6
files are solved in seconds. All values are correct, but we have
lost the reporting variables.<br>
<br>
So it looks as if you will have to do some coding. It may be
easiest to leave the model generator as is and write a driver - a
day's work?<br>
<br>
John Forrest<br>
On 24/06/16 16:01, Paul Fenton wrote:<br>
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<p>Hi Everyone,</p>
<p><br>
</p>
<p>This is my first post on the CBC mailing list. I have been
using the CBC command line tool for the past two years with
great success <span id="ms-rterangepaste-start"></span><span>(v2.7.7
- AMPL build but using GMPL)</span><span
id="ms-rterangepaste-end"></span>. Thanks to everyone who
has contributed to this open source project!</p>
<p><br>
</p>
<p>Within my MIP model, there is a specific index, where for
each different value of this index, there is an entirely
separable subproblem, with no shared decision variables or
constraints. It is desirable for me to package them all up as
one model to save on coding overhead.</p>
<p><br>
</p>
<p>The problem is, my data sets have grown to the point where my
full problem now has hundreds of sub-problems. It seems that
as the number of sub problems grows, the time taking to solve
is highly non-linear and becoming hard to wait for.</p>
<p><br>
</p>
<p>My fallback solution is to send each sub-problem to CBC in
series, and collect the outputs together, but I was hoping
someone may be able to suggest a simple command line option to
help CBC "see" the problem separability.</p>
<p><br>
</p>
<p>I appreciate any help anyone can provide on this topic, and
am available to provide more detail or an example file if it
would be helpful.</p>
<p><br>
</p>
<p>Thanks,</p>
<p><br>
</p>
<p>Paul</p>
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