daeoptions

Description

If it exists in the dae function calling context the variable %DAEOPTIONS the dae function use it to sets options.

This daeoptions function interactively displays a command which should be executed to set various options of the dae solver.

The dae function checks if this variable exists and in this case it uses it. For using default values you should clear this variable. Note that daeoptions does not create this variable. To create it you must execute the command line displayed by daeoptions.

The variable %DAEOPTIONS is a list with the following elements:

list(tstop,imode,band,maxstep,stepin,nonneg,isest)

The default value is:

list([],0,[],[],[],0,0)

The meaning of the elements is described below.

tstop

a real scalar or an empty matrix, gives the maximum time for which g is allowed to be evaluated. An empty matrix means "no limits" imposed for time.

imode

if it is 0 dae returns only the user specified time point values, and if it is 1 dae returns its intermediate computed values.

band

a two components vector which give the definition [ml,mu] of band matrix computed by jac;

r(i - j + ml + mu + 1,j) = dg(i)/dy(j)+cj*dg(i)/dydot(j). If jac returns a full matrix set band=[]

maxstep

a scalar or an empty matrix, the maximum step size, empty matrix means "no limitation".

stepin

a scalar or an empty matrix, the minimum step size, empty matrix means "not specified".

nonneg

a scalar, must be set to 0 if the solution is known to be non negative . In the other case it must be set to 1.

isest

a scalar, must be set to 0 if the given initial condition is compatible: g(t0,x0,xdot0)=0, and set to 1 if xdot0 is just an estimation.

See Also

• dae — Differential algebraic equations solver