RE: [Help-glpk] Irrational numbers

[Meketon, Marc]

Your semantics are incorrect.

 

Irrational means the number can not be represented as P/Q, where P and Q are integers.

 

For example, 1/3 is not irrational.  It is a rational number that is repeating in the base 10 numbering system.

 

The sqrt(2) is irrational.

 

Note that your proposed fix – to represent the objective value using only integer coefficients – is not a fix in general since the course of the linear/integer program will probably have many non-integer values in the tableau.

 

More importantly, note that your problem has multiple optimal.  x_1 = 0, x_2 = 6 is feasible with objective value of 1.

 

Your proposed solution of x_1=2, x_2=2 is feasible, with the same objective value of 1.

 

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From: address@hidden [mailto:address@hidden On Behalf Of Vijay Patil
Sent: Monday, August 11, 2008 2:02 PM
To: address@hidden
Subject: [Help-glpk] Irrational numbers

 

In one of application using GLPK, I am facing a problem because of not being able to represent irrational numbers/values correctly (as obj. func. coeff.).
Actually these values are dual values and are obtained from glpk itself. Since they are approximated there is a problem (loss of information).

If you have some experience/expertize dealing with irrational numbers or knowledge of floating point representation, you might be interested in
having a look at the problem.

http://code.google.com/p/cspsol/issues/detail?id=1#c2

Any workarounds to deal with this problem?

Thanks
--
Vijay Patil

 

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