octave ode45 'events' error

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I am running code in Octave that uses the odepkg 0.8.4. The first .m file called 'poin2.m' is used for getting a Poincare plot. The ode45 command in this file calls the 'spp.m' function.

clc;clear;
OMEG=1.02;
trans=2000;
N=2000;
xfin=zeros(N+1,2);
options=odeset('RelTol',1e-9,'AbsTol',1e-9,'events','on');
 xin=0.2;
 xdin=-0.2;
for i=1:trans
    if rem(i,50)==0 
       disp(i);
   end
    [t,x,te,xe,ie]=ode45('spp',[0 2*pi/OMEG],[xin xdin],options);
    xin=x(end,1);
    xdin=x(end,2);
end
 xfin(1,1)=xin;
 xfin(1,2)=xdin;
disp('Steady state starts');
for i=1:N
   if rem(i,50)==0 
       disp(i);
   end
[t,x,te,xe,ie]=ode45('spp',[0 2*pi/OMEG],[xin xdin],options);

xin=x(end,1);
xdin=x(end,2);
xfin(i+1,1)=x(end,1);
xfin(i+1,2)=x(end,2);
end

The function 'spp.m' contains the piecewise linear ODE to be integrated along with the required 'events' function.

function [xdot,isterminal,dircn]=spp(t,x,flag)
omega=1.02;
alpha=-0.01;q0=0.01;zhi=0.07;epsilon1=0.7;epsilon2=0.005;%epsilon2=0;temp=1;
if nargin<3 || isempty(flag)
if x(1)>1
    fh=x(1)-(1-alpha);
elseif x(1)<-1
    fh=x(1)+(1-alpha);
else
  fh=alpha*x(1);
end
xdot=[x(2);-2*zhi*x(2)-(1+2*epsilon2*cos(omega*t))*fh+q0+(omega^2)*epsilon1*cos(omega*t);]; 
else
        switch flag
        case 'events'
        xdot=x(1)^2-1;
        isterminal=0;
        dircn=0;
        otherwise
        error('function not programmed');
        end;
end;

The code runs well in MATLAB but in Octave the following error shows up:

error: Unknown parameter name "events"
error: called from:
error:   C:\Software\Octave-3.6.4\share\octave\packages\odepkg-0.8.4\odepkg_stru
cture_check.m at line 308, column 11
error:   C:\Software\Octave-3.6.4\share\octave\packages\odepkg-0.8.4\odeset.m at
 line 104, column 10
error:   C:\Software\Octave-3.6.4\share\octave\packages\odepkg-0.8.4\poin2.m at
line 12, column 8

Line 12 in 'poin2.m' is actually Line 6 in the first code that is posted. I have searched a lot for this problem in 'events' but did not find a solution. Can someone help me out?

asked 57 secs ago

zynga

1

octave ode45 'events' error