How to set values calculated from one ode45 as parameters to another ode45?

Hi

I have 2 defined functions files (F1,F2) + main file. F1 depends on y and F2 depends on T. I call ode45 in main file for F1 to calculate y values. Then I want to call ode 45 for F2 which calculates values T, but needs calculated values from F1. How should I then define (or put) y values in F2 or main file so it will take y values automatically?

Thanks

[Torsten]

Why don't you solve for y and T together in one function ?

[Martin Pecha]

first - I am beginner and that did not come up to my head second - I would like to possibly keep functions in separate files for transparency as one function file simulates concetrations and another simulates heats in battery.

[Torsten]

You can easily call the two separate functions from one ODE function file, but for numerical reasons, you should solve the two equations together.

[T,Z] = ode45(@fun,...)
...

function dz = fun(t,z)

y = z(1);
T = z(2);
...

[Martin Pecha]

and if I have two systems of diff equations F1(t,y) and F2(t,y,T) - is it possible to call them together in ode without rewriting it?

[Torsten]

function dz = fun(t,z)

n1 = ...;
n2 = ...;
y = z(1:n1);
T = z(n1+1:n1+n2);
dF1 = F1(t,y);
dF2 = F2(t,y,T);
dz = [dF1;dF2];

end

where F1 and F2 contain your separate two systems of differential equations.

[Martin Pecha]

It is still not working, dont know why. I have

 function dz = fun(t,z)
n1 = 10;
n2 = 4;
y = z(1:n1);
T = z(n1+1:n1+n2);
dmodel = model(t,y);
dteplo = teplo(t,y,T);
dz = [dmodel;dteplo];
end

my first function

 function [dTdt] = teplo (t,y,T)
global par
VC=par.VC; %volume of one cell [m3]
VT=par.VT; %volume of tank [m3]
QC=par.QC; %flow rate in cell [m3/s]
QS=par.QS; %flow rate of stack [m3/s]
i=par.i; %current flowing insinde [A]
F=par.F;
% K2=par.K2;
% K3=par.K3;
% K4=par.K4;
% K5=par.K5;
k2=par.k2;
k3=par.k3;
k4=par.k4;
k5=par.k5;
S=par.S; %membrane area
d=par.d; %thickness of membrane
Ncell=par.Ncell;%number of cell
rho=par.rho;
Cp=par.Cp
Vp=par.Vp
Ux=par.Ux
Uy=par.Uy
Uz=par.Uz
Uend=par.Uend
Up=par.Up
Ut=par.Ut
Ax=par.Ax
Ay=par.Ay
Az=par.Az
Ap=par.Ap
Tair=par.Tair
Ttinn=par.Ttinn
Ttinp=par.Ttinp
H24=par.H24
H34=par.H34
H43=par.H43
H53=par.H53
H54=par.H54
H23=par.H23
r=par.r
Wpump=par.Wpump
%parameters
Tinp=T(1);
Tinn=T(2);
T1=T(3);
T2=T(4);
% cCV2n=y(5);
% cCV3p=y(6);
% cCV3n=y(7);
% cCV4p=y(8);
% cCV4n=y(9);
% cCV5p=y(10);
dTdt=zeros(4,1);
% mass tank balance
dTdt(1)=(rho*Cp*QS*(Ttinp-Tinp)+Up*Ap*(Tair-Tinp)+Wpump)/(rho*Cp*Vp);
dTdt(2)=(rho*Cp*QS*(Ttinn-Tinn)+Up*Ap*(Tair-Tinn)+Wpump)/(rho*Cp*Vp);
%mass cell balance
dTdt(3)=(rho*Cp*QC*(Tinp-T1)+rho*Cp*QC*(Tinn-T1)+Ux*Ax*(T2-T1)+Uend*Ax*(Tair-T1)+2*Uy*Ay*(Tair-T1)+Uz*Az*(Tair-T1)+k2*cCV2n/d*S*(-H24)+k3*cCV3n/d*S*(-H34)+k4*cCV4p/d*S*(-H43)+k5*cCV5p/d*S*(-H53)+i*i*r*Ax)/(rho*Cp*VC);
dTdt(4)=(rho*Cp*QC*(Tinp-T2)+rho*Cp*QC*(Tinn-T2)+Ux*Ax*(T1-T2)+Uend*Ax*(Tair-T2)+2*Uy*Ay*(Tair-T2)+Uz*Az*(Tair-T2)+k2*cCV2n/d*S*(-H24)+k3*cCV3n/d*S*(-H34)+k4*cCV4p/d*S*(-H43)+k5*cCV5p/d*S*(-H53)+i*i*r*Ax)/(rho*Cp*VC);

my second function

 function [dydt] = model(t,y)
global par
VC=par.VC; %volume of one cell [m3]
VT=par.VT; %volume of tank [m3]
QC=par.QC; %flow rate in cell [m3/s]
QS=par.QS; %flow rate of stack [m3/s]
F=par.F;
i=par.i; %current flowing insinde [A]
k2=par.k2;
k3=par.k3;
k4=par.k4;
k5=par.k5;
S=par.S; %membrane area
d=par.d; %thnickness of membrane
Ncell=par.Ncell; %number of cell
%parameters
cTV2=y(1);
cTV3=y(2);
cTV4=y(3);
cTV5=y(4);
cCV2n=y(5);
cCV3p=y(6);
cCV3n=y(7);
cCV4p=y(8);
cCV4n=y(9);
cCV5p=y(10);
dydt=zeros(10,1);
%mass tank balance
dydt(1)=((QC*cCV2n)-QS*cTV2)/VT;
dydt(2)=((QC*cCV3n)-QS*cTV3)/VT;
dydt(3)=((QC*cCV4p)-QS*cTV4)/VT;
dydt(4)=((QC*cCV5p)-QS*cTV5)/VT;
%mass cell balance
dydt(5)=(QC*(cTV2-cCV2n)+i/F-k2*cCV2n/d*S-2*k5*cCV5p/d*S-k4*cCV4p/d*S)/VC*2;
dydt(6)=0;
dydt(7)=(QC*(cTV3-cCV3n)-i/F-k3*cCV3n/d*S+3*k5*cCV5p/d*S+2*k4*cCV4p/d*S)/VC*2;
dydt(8)=(QC*(cTV4-cCV4p)-i/F-k4*cCV4p/d*S+3*k2*cCV2n/d*S+2*k3*cCV3n/d*S)/VC*2; 
dydt(9)=0; 
dydt(10)=(QC*(cTV5-cCV5p)+i/F-k5*cCV5p/d*S-2*k2*cCV2n/d*S-k3*cCV3n/d*S)/VC*2;

call ode in main file

 y0=zeros(1,14);
y0(1)=cTV2n0;
y0(2)=cTV3n0;
y0(3)=cTV4p0;
y0(4)=cTV5p0;
y0(5)=cTV2n0;
y0(6)=0;
y0(7)=cTV3n0;
y0(8)=cTV4p0;
y0(9)=0;
y0(10)=cTV5p0;
y0(11)=Tinit;
y0(12)=Tinit;
y0(13)=Tinit;
y0(14)=Tinit;
tt = 0:(1/60):(30*60/60);
options = odeset('abstol',1e-6,'reltol',1e-6);
    [t,z] = ode45(@fun,tt,y0,options);

[Torsten]

Uncomment the lines

% cCV2n=y(5);
% cCV3p=y(6);
% cCV3n=y(7);
% cCV4p=y(8);
% cCV4n=y(9);
% cCV5p=y(10);

or set the variables to meaningful values.

Best wishes

Torsten.

[Martin Pecha]

Thank you very much! It seems to be working. The problem was there and that I missplaced O.5 with 0:5 in one of konstants. What a hell because of this small mistake!