## Friday, August 12, 2011

### R: Solve System of ODE (ordinary differential equation)s.

R: Solve System of ODE (ordinary differential equation)s.

lsoda {odesolve} - R Documentation - Solve System of ODE (ordinary differential equation)s.

Description

Solving initial value problems for stiff or non-stiff systems of first-order ordinary differential equations (ODEs), The R function lsoda provides an interface to the Fortran ODE solver of the same name, written by Linda R. Petzold and Alan C. Hindmarsh. The system of ODE's is written as an R function (which may, of course, use .C, .Fortran, .Call, etc., to call foreign code) or be defined in compiled code that has been dynamically loaded. A vector of parameters is passed to the ODEs, so the solver may be used as part of a modeling package for ODEs, or for parameter estimation using any appropriate modeling tool for non-linear models in R such as optim, nls, nlm or nlme.

References

Hindmarsh, Alan C. (1983) ODEPACK, A Systematized Collection of ODE Solvers; in p.55–64 of Stepleman, R.W. et al.[ed.] (1983) Scientific Computing, North-Holland, Amsterdam.

Petzold, Linda R. (1983) Automatic Selection of Methods for Solving Stiff and Nonstiff Systems of Ordinary Differential Equations. Siam J. Sci. Stat. Comput. 4, 136–148.

lsoda {deSolve} - R Documentation - General Solver for Ordinary Differential Equations (ODE), Switching Automatically Between Stiff and Non-stiff Methods - http://hosho.ees.hokudai.ac.jp/~kubo/Rdoc/library/deSolve/html/lsoda.html

Description

Solving initial value problems for stiff or non-stiff systems of first-order ordinary differential equations (ODEs).

The R function lsoda provides an interface to the Fortran ODE solver of the same name, written by Linda R. Petzold and Alan C. Hindmarsh.

The system of ODE's is written as an R function (which may, of course, use .C, .Fortran, .Call, etc., to call foreign code) or be defined in compiled code that has been dynamically loaded. A vector of parameters is passed to the ODEs, so the solver may be used as part of a modeling package for ODEs, or for parameter estimation using any appropriate modeling tool for non-linear models in R such as optim, nls, nlm or nlme

lsoda differs from the other integrators (except lsodar) in that it switches automatically between stiff and nonstiff methods. This means that the user does not have to determine whether the problem is stiff or not, and the solver will automatically choose the appropriate method. It always starts with the nonstiff method.