# ex_andrews: Andrews Squeezing Mechanism, Index 3 DAE In deTestSet: Test Set for Differential Equations

## Description

The andrews problem describes the motion of 7 rigid bodies connected by joints without friction

It is a non-stiff second order differential algebraic equation of index 3, consisting of 14 differential and 13 algebraic equations

## Usage

 ```1 2 3``` ```andrews (times = seq(0, 0.03, by = 0.03/100), yini = NULL, dyini = NULL, parms = list(), printmescd = TRUE, method = mebdfi, atol = 1e-7, rtol = 1e-7, maxsteps = 1e+05, ...) ```

## 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. `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, `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 `printmescd ` if TRUE the mixed error significant digits computed using the reference solution at time 0.03 are printed `method ` the solver to use `maxsteps ` maximal number of steps per output interval taken by the solver `... ` additional arguments passed to the solver .

## Details

The default parameters are: parameter <- c(m1 = .04325, m2 = .00365, m3 = .02373, m4 = .00706 , m5 = .07050, m6 = .00706, m7 = .05498 , xa = -.06934, ya = -.00227 , xb = -0.03635, yb = .03273 , xc = .014 , yc = .072, c0 = 4530 , i1 = 2.194e-6, i2 = 4.410e-7, i3 = 5.255e-6, i4 = 5.667e-7, i5 = 1.169e-5, i6 = 5.667e-7, i7 = 1.912e-5, d = 28e-3, da = 115e-4,e=2e-2, ea = 1421e-5, rr = 7e-3, ra = 92e-5, l0 = 7785e-5, ss = 35e-3, sa = 1874e-5, sb = 1043e-5, sc = 18e-3, sd = 2e-2, ta = 2308e-5, tb = 916e-5, u = 4e-2, ua = 1228e-5, ub = 449e-5, zf = 2e-2, zt = 4e-2,fa=1421e-5, mom = 33e-3)

## 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.

## Author(s)

Karline Soetaert <[email protected]>

Francesca Mazzia <[email protected]>

## Examples

 ```1 2 3 4 5``` ```out <- andrews() plot(out, lwd = 2, which = 1:9) refsol <- reference("andrews") max(abs(out[nrow(out),-1] - refsol)/refsol) ```

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