# ex_wheelset: Wheel Set problem, mechanics, Index 2 IDE In deTestSet: Test Set for Differential Equations

## Description

Describes the motion of a simple wheelset on a rail track.

It is a differential algebraic equation of index 2, 17 equations.

## Usage

 ```1 2 3``` ```wheelset (times = seq(0, 10, by = 0.01), yini = NULL, dyini = NULL, parms = list(), printmescd = TRUE, method = mebdfi, atol = 1e-6, rtol = 1e-6, maxsteps = 1e5, ...) ```

## Arguments

 `yini ` the initial (state) values for the DE system. If `y` has a name attribute, the names will be used to label the output matrix. `dyini ` the initial derivatives of the state variables of the DE system. `times ` time sequence for which output is wanted; the first value of `times` must be the initial time. `parms ` list of parameters that overrule the default parameter values `method ` the solver to use `maxsteps ` maximal number of steps per output interval taken by the solver `atol ` absolute error tolerance, either a scalar or a vector, one value for each y. `rtol ` relative error tolerance, either a scalar or a vector, one value for each y, `printmescd ` if TRUE the mixed error significant digits computed using the reference solution at time 0.1 are printed `... ` additional arguments passed to the solver .

## Details

The default parameters are: MR = 16.08, G = 9.81, V = 30., RN0 = 0.1, LI1 = 0.0605, LI2 = 0.366, MA = 0.0, HA = 0.2, MU = 0.12 , XL = 0.19, CX = 6400., CZ = 6400. , E = 1.3537956, GG = 0.7115218, SIGMA = 0.28, GM = 7.92e10, C11 = 4.72772197, C22 = 4.27526987, C23 = 1.97203505, DELTA0 = 0.0262, AR = 0.1506, RS = 0.06, EPS = 0.00001, B1 = 0.0, B2 = 4.0

## Value

A matrix of class `deSolve` with up to as many rows as elements in `times` and as many columns as elements in `yini`, plus an additional column (the first) for the time value.

There will be one row for each element in `times` unless the solver returns with an unrecoverable error. If `yini` has a names attribute, it will be used to label the columns of the output value.

## Note

This model is implemented in R.

## Author(s)

Karline Soetaert <[email protected]>

Francesca Mazzia

## Examples

 ```1 2 3``` ```out <- wheelset() plot(out, which = 1:9, lwd = 2) max(abs(out[nrow(out), -1] - reference("wheelset"))) ```

deTestSet documentation built on May 29, 2017, 2:56 p.m.