Problem too many input arguments

Hi! We are having problems with ode45 this is our code:

 xstart=xp; %start koordinaten i x-led

 ystart=yp; %start koordinaten i y-led

 xprimstart=xpprim;% Stoftsvansens starthastighet i x-led

 yprimstart = ypprim;% Stoftsvansens starthastighet i y-led

 tstart=0;

 C=-1;
 Clista = [C];

 Xlista = [xstart];

 Ylista =[ystart];

 n=0; %vi tänker oss att vi beräknar kurvan för ca 30 partiklar

 while n<20 

    tslut = 2989; 

    [t,U] = ode45(@(t,U) ekvationssystem_ode(t,U,C),[0 tslut],[xstart ystart   xprimstart yprimstart]');

    x = U(:, 1); % tar ut varje x-koordinat från U
    y = U(:, 2);% tar ut varje y-koordinat från U
    C = C+0.1;
    Clista = [Clista,C]; %Lägger till varje nytt C värde i listan för C
    Xlista = [Xlista,x]; %Lägger till varje nytt x värde i listan för X
    Ylista = [Ylista,y]; %Lägger till varje nytt y värde i listan för Y
    n=n+1;
end

This is our funktion we us in ode45

function uprim =ekvationssystem_ode(t,U,C) %funktion som löser vårt ekvationssystem

s=(U(1)^2 + U(2)^2)^0.5; %definition för s givet i uppgiften uprim =[U(3),U(4),(-C*U(1))/(s^3),(-C*U(2))/(s^3)]'; %vektorn uprim som ODE45 använder för att returnera vektorn U

these are our errors. ...

Error using ekvationssystem_ode Too many input arguments.

Error in @(t,U)ekvationssystem_ode(t,U,C)

Error in odearguments (line 87) f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ode45 (line 113) [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

Error in mainprogram (line 68) [t,U] = ode45(@(t,U) ekvationssystem_ode(t,U,C),[0 tslut],[xstart ystart xprimstart yprimstart]');

Please help us! :)

[Adam]

Have you tried isolating the problem and calling

@(t,U) ekvationssystem_ode(t,U,C)

with arguments:

[0 tslut]

and

[xstart ystart   xprimstart yprimstart]'

outside of the ode45 function?

I can't see anything obviously wrong glancing at the code. I have never used ode45 so don't know anything about that, but it looks as though the error is independent of the use of the ode45 function and caused by your function handle passed to that.

Answer 1

[Torsten]

Maybe you have to replace

[t,U] = ode45(@(t,U) ekvationssystem_ode(t,U,C),[0 tslut],[xstart ystart xprimstart yprimstart]');

by

[t,U] = ode45(@(t,y) ekvationssystem_ode(t,y,C),[0 tslut],[xstart ystart xprimstart yprimstart]);

and

uprim =[U(3),U(4),(-C*U(1))/(s^3),(-C*U(2))/(s^3)]';

by

uprim =[U(3);U(4);(-C*U(1))/(s^3);(-C*U(2))/(s^3)];

?

Best wishes

Torsten.