Why doesn't ode stop when value equals zero ?

Sparmont Daniel-Henri

2015 4 月 5

0 回答

4 ビュー (30 日間)

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I'm working on a project for the University. I decided to use an event with ode15s solver : This solver simulates the speed and position of a car and the event makes the simulation stop as the car reaches the speed limit on a road. This solver is inside a for loop, simulating a different part of the road.

    Options=odeset('Events',@eventfunction);
    [T,Y,TE,YE,IE] = ode15s(@odefun,tspan,init,Options,indice,Theta,Omega,Cmax,Fmot,vref,l,lparcourue,Rho,S,Cx,f0,f2,mveh,g,atrans,btrans)

The event function's code is

function [value,isterminal,direction]=eventfunction(t,variables,indice,Theta,Omega,Cmax,Fmot,vref,l,lparcourue,Rho,S,Cx,f0,f2,mveh,g,atrans,btrans)
      value=variables(2)-vref;
      isterminal=1;
      direction=0;
      if(variables(1)>lparcourue+l)
          value=0;
      end
end

And odefun is defined as :

function derivee = odefun(t,variables,indice,Theta,Omega,Cmax,Fmot,vref,l,lparcourue,Rho,S,Cx,f0,f2,mveh,g,atrans,btrans)
      v = variables(2);
      F1 = Fmot;
      F2 = Faero(Rho,S,Cx,v);
      F3 = Frlt(f0,f2,mveh,g,Theta,v);
      F4 =Fgrav(mveh,g,Theta);
      M = me(atrans,btrans,indice,mveh);
      derivee = zeros(2,1);
      derivee(1) = v;
      derivee(2) = (F1-F2-F3-F4)/M;
end

For the first loop, everything is OK, but during the second loop, when the speed remains the same and the solver should stop imediately, it doesn't. I first tough my value had no zero, but after removing the semicolon after "value=..." I had :

value =
       0
value =
       0
value =
       0
value =
       0
value =
       0
value =
       0
value =
       0
value =
       0
value =
       0
value =
       0
value =
       0
T =
    1.0e+005 *
      0.0000
      0.1000
      0.2000
      0.3000
      0.4000
      0.5000
      0.6000
      0.7000
      0.8000
      0.9000
      1.0000
Y =
    1.0e+006 *
      0.0008    0.0000
      0.1396    0.0000
      0.2785    0.0000
      0.4174    0.0000
      0.5563    0.0000
      0.6952    0.0000
      0.8341    0.0000
      0.9730    0.0000
      1.1119    0.0000
      1.2508    0.0000
      1.3896    0.0000
TE =
       []
YE =
       []
IE =
       []