odeoptions — set options for ode solvers
odeoptions()
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