odeoptions

Scilab Function
Last update : 25/04/2007

odeoptions - set options for ode solvers

### Calling Sequence

  `odeoptions()`

### Description

This function interactively displays a command which should be executed to set various options of ode solvers. The global variable `%ODEOPTIONS` sets the options.

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

The variable `%ODEOPTIONS` is a vector with the following elements:

    [itask,tcrit,h0,hmax,hmin,jactyp,mxstep,maxordn,maxords,ixpr,ml,mu]

The default value is:

    [1,0,0,%inf,0,2,500,12,5,0,-1,-1]

The meaning of the elements is described below.

`itask` 1 : normal computation at specified times 2 : computation at mesh points (given in first row of output of `ode` ) 3 : one step at one internal mesh point and return 4 : normal computation without overshooting `tcrit` 5 : one step, without passing `tcrit` , and return

`tcrit` assumes `itask` equals 4 or 5, described above

`h0` first step tried

`hmax` max step size

`hmin` min step size

`jactype` 0 : functional iterations, no jacobian used (`"adams"` or `"stiff"` only) 1 : user-supplied full jacobian 2 : internally generated full jacobian 3 : internally generated diagonal jacobian (`"adams"` or `"stiff"` only) 4 : user-supplied banded jacobian (see `ml` and `mu` below) 5 : internally generated banded jacobian (`see` ml and `mu` below)

`maxordn` maximum non-stiff order allowed, at most 12

`maxords` maximum stiff order allowed, at most 5

`ixpr` print level, 0 or 1

`ml` ,`mu` If `jactype` equals 4 or 5, `ml` and `mu` are the lower and upper half-bandwidths of the banded jacobian: the band is the i,j's with i-ml <= j <= ny-1. If `jactype` equals 4 the jacobian function must return a matrix J which is ml+mu+1 x ny (where ny=dim of y in ydot=f(t,y)) such that column 1 of J is made of mu zeros followed by df1/dy1, df2/dy1, df3/dy1, ... (1+ml possibly non-zero entries) column 2 is made of mu-1 zeros followed by df1/dx2, df2/dx2, etc

### See Also

`ode` ,