# multirunge: Runge-Kutta numerical solver (single point, multivariate) In nlsrk: Runge-Kutta Solver for Function nls()

## Description

Solves numerically an initial conditions problem for a set of Ordinary Differential Equations (ODE) by Runge-Kutta 4 method. Integrates numerically the equations from tmin to tmax by steps of dt.

## Usage

 `1` ```multirunge(y0, tmin, tmax, dt, param, sys) ```

## Arguments

 `y0` Numerical vector : initial conditions (as many elements as equations in sys) `tmin` Minimum value of the independent variable (generally the time) `tmax` Maximum value of the independent variable `dt` Time increment (default = 0.01) `param` Numerical vector providing the parameters for sys `sys` The set of functions giving the right sides of the ODEs

## Details

`sys` must be provided by the user. Please edit the object `sys` (see `?sys` and examples)

## Value

A numerical vector of nfunct elements. Nfunct is the number of unknown functions of `sys` determined by the function as `length(sys())`

## Note

Should seldom be used independently. Most often it will be called by evrunge

## Author(s)

Jean-Sebastien Pierre
[email protected]

`evrunge`, `sys`, `nls`
 `1` ``` multirunge(y0=c(1000,0),tmin=0,tmax=30,dt=0.01,param=c(1,1),sys=sys) ```