ode15s struggle: Implement ODE solver within GUI (without GUIDE)

Hi, I am building a GUI wrapper for my chemical engineering project.

I wrote the calculation functions separately to be sure they work correctly and everything worked fine. Now, when I wrapped everything in a GUI, I started having trouble with ODE solver which apparently is not working. I am quite a beginner using Matlab, only use it occasionally for study purposes, never for a GUI before but I suspect that the trouble is with passing the parameters between app data and the model function (code attached) as they change with user inputs.

I tried multiple ways to solve this already - external function file for "model", write it as internal function as well as nested function inside ''chlazeni" function and nothing worked neither have I found any useful answer among the Community.

Thanks in advance for any help!

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I am running the "chlazeni" function from "reaktordatabase" function, which is a ValueChangedFcn of a list box

function reaktordatabase(hObject,eventData,handles,fig)

%'BR15K','BR4K','BR2K','BR200','BR300','SHT15','BR1440'

mdot = get(handles.edt1,'Value'); %[kg/s], hm.prutok chl.vody

setappdata(fig,'mdot',mdot)

tIN = get(handles.edt2,'Value'); %[°C], teplota vstupujici chl.vody

setappdata(fig,'tIN',tIN)

otacky = get(handles.edt3,'Value');

setappdata(fig,'otacky',otacky);

lbxValue = get(handles.lbx,'Value');

if strcmp(lbxValue,'BR15K')

disp(lbxValue)

V = 15; %[m3], objem reaktoru

D = 2.0; %[m], prumer reaktoru

H = 5.1; %[m], vyska reaktoru celk.

h = 4.5; %[m], vyska duplikace

A = 4.115; %[m2], teplosmenna plocha

VB = 6; %[m3], objem vsadky

Q0 = 198595.470/1000; %[kW], teplo k odebrani

setappdata(fig,'V',V)

setappdata(fig,'D',D)

setappdata(fig,'H',H)

setappdata(fig,'h',h)

setappdata(fig,'A',A)

setappdata(fig,'VB',VB)

setappdata(fig,'Q0',Q0)

pomocne_vypocty(handles,fig)

chlazeni(handles,fig)

the "chlazeni" function itself looks like:

function chlazeni(handles,fig)

data = getappdata(fig);

N = data.N;

tstep = data.tstep;

% pocatecni podminky

tOUT0 = 25*ones(N,1);

setappdata(fig,'tOUT0',tOUT0)

tB0 = get(handles.edt2,'Value');

setappdata(fig,'tB0',tB0)

y0 = [tB0; tOUT0];

setappdata(fig,'y0',y0)

pars = [data.mdot data.cpW data.alfaW data.d data.lambda316L data.A,...

data.V data.alfaB data.rhoB data.mB data.cpB data.tIN,...

data.N data.tstep data.Vdot]';

assignin('base','pars',pars);

% integrace

opt = odeset('Events',@EventsFcn);

tEnd = 16*3600; %integracni cas, v sekundach

tspan = 0:tstep:tEnd;

[tt, yy] = ode45(@(t,y) model(t,y,pars),tspan,y0,opt);

tt = tt/3600; %integracni cas, v hodinach

[~,Q] = cellfun(@(t,y) model(t,y.',pars), num2cell(tt), num2cell(yy,2),'uni',0);

Q = cell2mat(Q);

Qcumul = trapz(tt,Q/1000) %[kW]

setappdata(fig,'Qcumul',Qcumul)

set(handles.edt5,'Value',Qcumul)

M = size(yy);

M = M(2);

t_stred = mean(yy(:,M))

setappdata(fig,'t_stred',t_stred)

t_max = max(yy(:,M))

setappdata(fig,'t_max',t_max)

% plotting results

for k = 2:4:M

plot(handles.ax1,tt,yy(:,k))

hold(handles.ax1,'on')

end

hold(handles.ax1,'off');

axis(handles.ax1,'tight');

xlabel(handles.ax1,'Čas [h]');

ylabel(handles.ax1,'Teplota výstupní chl.vody [°C]');

txt = {['t_max: ' num2str(t_max)],['t_střední: ' num2str(t_stred)]};

handles.str = uilabel('Parent',fig,'Position',[700 390 70 45],'Text',txt,...

'HorizontalAlignment','right','VerticalAlignment','center');

plot(handles.ax2,tt,yy(:,1));

axis(handles.ax2,'tight');

xlabel(handles.ax2,['Čas [h] - doba chlazení: ',num2str(tt(end)),' h'])

ylabel(handles.ax2,'Teplota vsádky [°C]');

axis(handles.ax2,'tight');

plot(handles.ax3,tt,Q/1000);

axis(handles.ax3,'tight');

xlabel(handles.ax3,'Čas [h]');

ylabel(handles.ax3,'\Sigma Q [kW]');

axis(handles.ax3,'tight');

end

and the original "model" function that is the input in ode15s, as was before using GUI (=working code) is:

function [dTdt,Q] = model(~,Tvec,pars)

% rozbaleni parametru

% pars = [mdot cpW alfaW d lambda A V alfaB rhoB mB cpB tIN N tstep Vdot]';

mdot = pars(1);

cpW = pars(2);

alfaW = pars(3);

d = pars(4);

lambda316L = pars(5);

A = pars(6);

V = pars(7);

alfaB = pars(8);

rhoB = pars(9);

mB = pars(10);

cpB = pars(11);

tIN = pars(12);

N = pars(13);

tstep = pars(14);

Vdot = pars(15);

tRef = 0;

mW = ((0.0024*4.5)/(Vdot/3600))*mdot; % Amax(m2)*výška duplikace(m)*rho(kg/m3)*čas(s) "zádrž vody v plášti"

K = 1/(d/lambda316L+1/alfaW+1/alfaB);

F = zeros(N+1,1);

Q = zeros(N+1,1);

F(1) = mdot*cpW*(tIN-tRef);

Q(1) = K*A/N*(Tvec(1)-tIN);

for i=2:N+1

Q(i) = K*A/N*(Tvec(1)-Tvec(i));

F(i) = mdot*cpW*(Tvec(i)-tRef);

end

for j = 2:N+1

dTdt(j) = (F(j-1)-F(j)+Q(j))/((mW/N)*cpW);

end

Q = sum(Q);

dTdt(1) = -Q/(cpB*mB);

dTdt = dTdt';

[Cris LaPierre]

Attach your *.m and *.fig files using the paperclip icon. It is much easier to help if we can run the gui ourselves.

[Kristyna]

Thank you for the note, corrected.

[Cris LaPierre]

Can you share an example script of your ode working correctly before you wrapped it in a gui?

[Stephen23]

One of the main benefits of not using GUIDE is that you are not restricted to how GUIDE passes data between callbacks:

https://www.mathworks.com/help/matlab/creating_guis/share-data-among-callbacks.html

The best approach when you have lots of parameters is to use nested functions, which would mean that you do not need all of those getappdata/setappdata calls, but could simply refer to exactly the same variables in the parent workspace.

https://www.mathworks.com/matlabcentral/answers/483657-how-to-create-a-gui

[Kristyna]

@Stephen

Ok, update: the parameters are passed inside "model" function just fine, last thing that is calculated correctly is F(1) inside this function. The rest is not calculated & the ode15s is not working properly, which is weird as it works just fine standing alone - I uploaded one more file (reaktor_BR15K.m) which shows what the code should be doing (without major user interaction).

My problem seems similar to this question, except the nesting does not work for me - may be there's a nuance I cannot see due to lack of experience..?

[Kristyna]

@Cris LaPierre I uploaded the "reaktor_BR15K.m" to show how the whole thing should work.

With th GUI, I want to allow the user to change values of some of the parameters and recalculate the integration accordingly.

Answer 1

[Kristyna]

Found the error, thanks everyone for their time: I lost my head in the code!

Anyway, your inputs were incredibly useful and I will apply them to make my code more efficient.

Thanks again!!