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Basic QCQP solver interface for Xpress Optimizer Description Language extensions provided by this module:
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Data Files catenary_mx.mos (!********************************************************************* Mosel NI examples ================= file catenary_mx.mos ```````````````````` QCQP problem (linear objective, convex quadratic constraints) Based on AMPL model catenary.mod (Source: http://www.orfe.princeton.edu/~rvdb/ampl/nlmodels/ ) This model finds the shape of a hanging chain by minimizing its potential energy. - Using the myqxprs module - (c) 2008 Fair Issac Corporation author: S. Heipcke, May 2008, rev. Apr. 2018 *********************************************************************!) model "catenary - myqxprs version" uses "myqxprs" parameters N = 100 ! Number of chainlinks L = 1 ! Difference in x-coordinates of endlinks H = 2*L/N ! Length of each link end-parameters declarations RN = 0..N x: array(RN) of mpvar ! x-coordinates of endpoints of chainlinks y: array(RN) of mpvar ! y-coordinates of endpoints of chainlinks PotentialEnergy: linctr ! Objective function Link: array(range) of nlctr ! Constraints end-declarations forall(i in RN) x(i) is_free forall(i in RN) y(i) is_free ! Objective: minimise the potential energy PotentialEnergy:= sum(j in 1..N) (y(j-1)+y(j))/2 ! Bounds: positions of endpoints ! Left anchor x(0) = 0; y(0) = 0 ! Right anchor x(N) = L; y(N) = 0 ! Constraints: positions of chainlinks forall(j in 1..N) Link(j):= (x(j)-x(j-1))^2+(y(j)-y(j-1))^2 <= H^2 ! Setting start values forall(j in RN) setinitval(x(j), j*L/N) forall(j in RN) setinitval(y(j), 0) ! Configuration of the solver setparam("myxp_verbose", true) ! Solve the problem minimise(PotentialEnergy) ! Solution reporting if getprobstat<>MYXP_OPT and getprobstat<>MYXP_UNF then writeln("No solution available. Solver status: ", getprobstat) else writeln("Solution: ", getobjval) forall(j in RN) writeln(strfmt(getsol(x(j)),10,5), " ", strfmt(getsol(y(j)),10,5)) end-if end-model | |||||||||||
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