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.TH odeoptions G "February 1998" "Scilab Group" "Scilab Function"
.so ../sci.an
.SH NAME
odeoptions - sets options for ode solvers
.SH CALLING SEQUENCE
.nf
odeoptions()
.fi
.SH DESCRIPTION
This functions interactively displays a command which
should be executed to set various options of ode solvers.
The global variable \fV%ODEOPTIONS\fR sets the options.
CAUTION: the \fVode\fR function checks if this variable
exists and in this case uses it. For using default
values you should clear this variable. Note that \fVodeoptions\fR
does not create this variable. To create it you must execute
the command line displayed by \fVodeoptions\fR.
The variable \fV%ODEOPTIONS\fR is a vector with the following elements:
\fV[itask,tcrit,h0,hmax,hmin,jactyp,mxstep,maxordn,maxords,ixpr, ml,mu]\fT
The default value is: \fV[1,0,0,%inf,0,2,500,12,5,0,-1,-1]\fR.
The meaning of the elements is described below.
\fVitask\fR
1 : normal computation at specified times
2 : computation at mesh points (given in first row of output of \fVode\fR)
3 : one step at one internal mesh point and return
4 : normal computation without overshooting \fVtcrit\fR
5 : one step, without passing \fVtcrit\fR, and return
\fVtcrit\fR
assumes \fVitask\fR equals 4 or 5, described above
\fVh0\fR
first step tried
\fVhmax\fR
max step size
\fVhmin\fR
min step size
\fVjactype\fR
0 : functional iterations, no jacobian used (\fV'adams'\fR or
\fV'stiff'\fR only)
1 : user-supplied full jacobian
2 : internally generated full jacobian
3 : internally generated diagonal jacobian (\fV'adams'\fR or
\fV'stiff'\fR only))
4 : user-supplied banded jacobian (\fVsee\fR ml and \fVmu\fR below)
5 : internally generated banded jacobian (\fVsee\fR ml and \fVmu\fR below)
\fVmaxordn\fR
maximum non-stiff order allowed, at most 12
\fVmaxords\fR
maximum stiff order allowed, at most 5
\fVixpr\fR
print level, 0 or 1
\fVml\fR, \fVmu\fR
If \fVjactype\fR equals 4 or 5, \fVml\fR and \fVmu\fR are the lower
and upper half-banwidths of the banded jacobian: the band is the
i,j's with i-ml <= j <= ny-1
If \fVjactype\fR 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'
.SH SEE ALSO
ode
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