ode 45 not enough input argument

this is my fynction.it says Error using my_ode (line 18) Not enough input arguments. can you help?

function df=diff2(t,f)

Tc=60+5*(60-25)
nw=20
k0=5e10
x=15000
c=-9020
pa=14.384
pw=55.382
pb=13.668
cpa=125
cpw=75
cpb=250
a=-55570
b=-349700

df(1)=-f(6)*f(1);
df(2)=0;
df(3)=-df(1);
df(4)=(x*(Tc-f(4))-df(1)*a-df(3)*b-(df(1)*cpa+df(3)*cpb+df(2)*cpw)*f(4))/(na*cpa+nb*cpb+nw*cpw);
f(5)=(na/pa)+(nb/pb)+(nw/pw);
f(6)=k0*exp(c/f(4));
end 
function my_ode()
[T,F]=ode45(@diff2,[0 100],[10 20 0 333 1.056 8.6e-2])

plot(T,F(:,1),'-',T,F(:,2),'-',T,F(:,3),'-',T,F(:,4),'-',T,F(:,5),'-',T,F(:,6),'-')
end

Answer 1

[Torsten]

function my_ode
[T,F]=ode15s(@diff2,[0 100],[10 20 0 333]);
plot(T,F(:,1),'-',T,F(:,2),'-',T,F(:,3),'-',T,F(:,4),'-')

function df=diff2(t,f)
Tc=60+5*(60-25);
nw=20;
k0=5e10;
x=15000;
c=-9020;
pa=14.384;
pw=55.382;
pb=13.668; 
cpa=125;
cpw=75; 
cpb=250;
a=-55570;
b=-349700;

df=zeros(4,1);
df(1)=-k0*exp(c/f(4))*f(1); 
df(2)=0; 
df(3)=-df(1); 
df(4)=(x*(Tc-f(4))-df(1)*a-df(3)*b-(df(1)*cpa+df(3)*cpb+df(2)*cpw)*f(4))/(na*cpa+nb*cpb+nw*cpw);

Best wishes

Torsten.

[maroubi maria]

you are the best!!!!!

[maroubi maria]

thank you a lot

[maroubi maria]

we still have a problem because it is plotting the df(1),df(2),df(3) ntc and not the f(1),f(2),f(3) ntc that we need. did we write wrong the equations or the code is wrong? thank you

[Torsten]

As written, MATLAB plots f(1),...,f(4) over T.

You can easily check this:

The first plot should start at 10, the second at 20, the third at 0 and the fourth at 333.

Best wishes

Torsten.

[maroubi maria]

actually the problem is that it keeps the initial values