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# 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 — solveur d'équations différentielles ordinaires

<< odedc | Equations Differentielles | Fonctions Elémentaires >> |