Re: [Help-glpk] Problem with absolute value

[Alessandro Saccoia]

Hi Reginald,
thank you for pointing me to that script. I took a look, and if I will run out 
of time I will definitely use it. The program is really cpu intensive and the 
alignment part is an intermediate result, so I will still try to use the 
library. dumping formatted data to disk and running another program would mean 
to wrap everything in a script and break my original program into two parts. 
still it's an option... thanks for your help, 
alessandro

On Jan 14, 2013, at 2:34 PM, Reginald Beardsley <address@hidden> wrote:

> Alessandro,
> 
> If you look here:
> 
> http://en.wikibooks.org/wiki/GLPK/Unix_Batch_Execution
> 
> at script tst2a, you'll see an example of generating MathProg data files in a 
> *nix command line environment which should be pretty much all you need.  It's 
> much less work than writing a custom program using the library calls.  It 
> also makes modifying the model much easier.
> 
> If you need to pull the data out of something messy send me a sample.  awk is 
> really good for tasks such as merging data from several sources or parsing 
> complex formats.
> 
> Have Fun!
> Reg
> 
> --- On Mon, 1/14/13, Alessandro Saccoia <address@hidden> wrote:
> 
>> From: Alessandro Saccoia <address@hidden>
>> Subject: Re: [Help-glpk] Problem with absolute value
>> To: "Jeffrey Kantor" <address@hidden>
>> Cc: "address@hidden" <address@hidden>
>> Date: Monday, January 14, 2013, 6:17 AM
>> Hi Jeff,
>> that works wonders! Now I would just like to find a way to
>> use the library instead of the executable, and insert all
>> this information programmatically. In the glpk docs it seems
>> that it's up to me to introduce all the variables and create
>> the A matrix, but from another answer I got in pvt it looks
>> like I can use this syntax and have the library do the
>> necessary calculations.
>> If I can't avoid reading the model from file, I would at
>> least like to be able to provide the data at runtime. Thanks
>> for your time!
>> Alessandro
>> 
>> On Jan 14, 2013, at 1:04 PM, Jeffrey Kantor <address@hidden>
>> wrote:
>> 
>>> Hi Alessandro,
>>> 
>>> I don't exactly the geometry, but here's a MathProg
>> model for your problem. If you want to try this out, cut and
>> paste it into the web page at http://www3.nd.edu/~jeff/mathprog/mathprog.html
>>> 
>>> Jeff 
>>> 
>>> 
>>> set N := 0..3;
>>> param q{N};
>>> param r{N};
>>> 
>>> param a := 0.95;
>>> param b := 1.05;
>>> 
>>> var z{N} >= 0;
>>> var s{N};
>>> 
>>> s.t. c1 {n in 0..3}: z[n] >= r[n] - s[n];
>>> s.t. c2 {n in 0..3}: z[n] >= s[n] - r[n];
>>> s.t. c3 {n in 0..2}: s[n+1] - s[n] >=
>> a*(q[n+1]-q[n]);
>>> s.t. c4 {n in 0..2}: s[n+1] - s[n] <=
>> b*(q[n+1]-q[n]);
>>> 
>>> minimize obj: sum{n in N} z[n];
>>> solve;
>>> 
>>> data;
>>> 
>>> param q :=
>>>      0    3
>>>      1    5
>>>      2    8
>>>      3   12 ;
>>>      
>>> param r :=
>>>      0    2
>>>      1    5
>>>      2    7
>>>      3   11 ;
>>>      
>>> end;
> 
> 
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