Hi everyone and Alberto, Numeric.LinearProgramming[1] provides a very nice interface for solving LP optimisation problems, and the well-known simplex algorithm itself. I must say I quite liked the interface it provides, simple yet sufficient. But, to my understanding, there is a confusion in the constructor name (symbols actually) for constraints. In LP, one needs to write constraints in the form of ==, <=, or >= only. You *cannot *write a constraint using strict inequalities. The algorithm has nothing wrong, but I guess it would be better to have constructor symbols right. See [2] If this is a design choice, I think it should explicitly be stated. Regards, [1] http://hackage.haskell.org/package/hmatrix-glpk [2] http://hackage.haskell.org/packages/archive/hmatrix-glpk/0.1.0/doc/html/Nume... -- Ozgur Akgun