Hello, I have a system of quadratic equations (results of a Hamiltonian optimization) which I need to find the roots for. Is there a package and/or function which will find the roots for a quadratic system? Note that I am not opimizing, but rather solving the first order conditions which come from a Hamiltonian. I am basically looking for something in R that will do the same thing as fsolve in Matlab. Thanks, John. =============================================Dr. John Janmaat Department of Economics Acadia University Tel: 902-585-1461
John Janmaat wrote:>Hello, > >I have a system of quadratic equations (results of a Hamiltonian optimization) >which I need to find the roots for. Is there a package and/or function which >will find the roots for a quadratic system? >Certainly you cxould use solve, see ?solve Alternatively you could go for a computer algebra system with an implemantation of groebner basis, and use an symbolic method. Kjetil> Note that I am not opimizing, but >rather solving the first order conditions which come from a Hamiltonian. I am >basically looking for something in R that will do the same thing as fsolve in >Matlab. > >Thanks, > >John. > >=============================================>Dr. John Janmaat >Department of Economics >Acadia University >Tel: 902-585-1461 > >______________________________________________ >R-help at stat.math.ethz.ch mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > > > >-- Kjetil Halvorsen. Peace is the most effective weapon of mass construction. -- Mahdi Elmandjra -- No virus found in this outgoing message. Checked by AVG Anti-Virus.
Kjetil Brinchmann Halvorsen wrote:> John Janmaat wrote: > >> Hello, >> >> I have a system of quadratic equations (results of a Hamiltonian >> optimization) >> which I need to find the roots for. Is there a package and/or >> function which >> will find the roots for a quadratic system? > > Certainly you cxould use solve, see > ?solve > Alternatively you could go for a computer algebra system with an > implemantation > of groebner basis, and use an symbolic method.I have looked into using solve. However, solve works on a system of linear equations (at least that is how I read it). I have a system of quadratic equations. They can be written to equate to zero, so that a non-linear system solver should do the trick. John.> Kjetil > >> Note that I am not opimizing, but >> rather solving the first order conditions which come from a >> Hamiltonian. I am >> basically looking for something in R that will do the same thing as >> fsolve in >> Matlab. >> >> Thanks, >> >> John. >> >> =============================================>> Dr. John Janmaat >> Department of Economics >> Acadia University >> Tel: 902-585-1461 >> >> ______________________________________________ >> R-help at stat.math.ethz.ch mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide! >> http://www.R-project.org/posting-guide.html >> >> >> >> >> > >-- =========================================Dr. John Janmaat Department of Economics Acadia University Wolfville, Nova Scotia, Canada.
Are you looking for a unique solution or families of solutions? Can't you turn a root-finding problem for a system of equations with a unique solution into an optimisation problem, anyway? E.g. You want to solve f1(x) = g1 f2(x) = g2 ... Why not optimise L(x) = (f1(x) - g1)^2 + (f2(x) - g2)^2 + ... with respect to x? If the minimum value is zero, then you are done; if it is greater than zero your original system does not have a solution. If you are in the complex domain the changes needed are obvious. V. : -----Original Message----- : From: r-help-bounces at stat.math.ethz.ch : [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of John Janmaat : Sent: Monday, 2 May 2005 12:48 AM : To: r-help at stat.math.ethz.ch : Subject: [R] Roots of quadratic system. : : : Hello, : : I have a system of quadratic equations (results of a : Hamiltonian optimization) : which I need to find the roots for. Is there a package : and/or function which : will find the roots for a quadratic system? Note that I am : not opimizing, but : rather solving the first order conditions which come from a : Hamiltonian. I am : basically looking for something in R that will do the same : thing as fsolve in : Matlab. : : Thanks, : : John. : : =============================================: Dr. John Janmaat : Department of Economics : Acadia University : Tel: 902-585-1461 : : ______________________________________________ : R-help at stat.math.ethz.ch mailing list : https://stat.ethz.ch/mailman/listinfo/r-help : PLEASE do read the posting guide! : http://www.R-project.org/posting-guide.html :