Coupled differential equations kinetic

Hello Im am trying to solve 3 coupled ODE's, with the plot related to the reduction of NO by with ammoniasulphate.

The issiue is that the differential equation i wrote do not seems to be coupled. First the initial condition for NH3 is zero, but that makes the rate of change 0. If i change the NH3 to a very small value then the system still not respond well (deacreasing NO over time) as chaning the stouchemtic coiffcient x1 does not change the NO concentration...... see attched. Thanks.

[Sulaymon Eshkabilov]

Could you please post your diff equations in order to read your code correctly?

[Niels Normann Sørensen]

Yes sorry, just posted the 3 ODE's as ZIP file.

Answer 1

[darova]

yprime and y are always connected

function [ yprime ] = calibration( t,y,par,par_cali,T,x1,O2)

Your input y were in wrong order. Try this

AS=y(1);
NH3=y(2);
NO=y(3);

Result

[darova]

OR (maybe) because of this parameter

L=c+(h/4)+s+(n/2)-(o/2); % Unnamed factor, haha

[Niels Normann Sørensen]

The calling of the initial conditions in the function file are in the right order as the vector in script is y_cali=[y_NO_in*x y_in_AS*x y_in_NH3*x]?

L has nothing to do with the ODE calculations.

[darova]

L has nothing to do with the ODE calculations.

It was a joke :)

I forgot about initial conditions. They need to be changed too

y_cali=[y_in_AS*x y_in_NH3*x y_NO_in*x]; % initial conditions 

ode45 function finds a solution using iterations

(You don't see these operations)

y1(i+1) = y1(i) + yprime1(i)*dt;            % simplified operations you don't see
y2(i+1) = y2(i) + yprime2(i)*dt;
%% - - -

[Niels Normann Sørensen]

YOU ARE THE BEST!!!!

Thanks!!!

[Niels Normann Sørensen]

I did not know that the order off the diff setup and intial conditions have to be the same.

Now the L comment is funny hahah!!

[darova]

You are welcome =)