(App Designer) Error using matlab.ui.control.EditField/set.Value (line 96) 'Value' must be a character vector - matlab

Question

So I am creating an app to find a value based on several inputs but hit an error as one of the outputs won't show.
This is the app layout
1
The problem is the total cost section won't show the value when I clicked the calculate button. The 'Q Optimal' works just fine.
2
the formula associated with the button on the right side looks like this:
dm=app.MinimumDemandEditField.Value;
dM=app.MaximumDemandEditField.Value;
tm=app.MinimumLeadTimeEditField.Value;
tM=app.MaximumLeadTimeEditField.Value;
r1=app.ReorderLevelEditField.Value;
Et = 0.5*(tm+tM);
vart = 1/12*(tM-tm)^2;
Ed = 0.5*(dm+dM);
vard = 1/12*(dM-dm)^2;
ED = 1/4*(dm+dM)*(tm+tM);
varD = 1/144*(3*(dm+dM)^2*(tM-tm)^2+3*(dM-dm)^2*(tm+tM)^2+(tM-
tm)^2*(dM-dm)^2);
gt = 1/(tM-tm);
fd = 1/(dM-dm);
fD = 1/((dM-dm)*(tM-tm));
f1=app.FixedCostEditField.Value;
c1=app.VariableCostEditField.Value;
h=app.HoldingCostEditField.Value;
s=50*c1;
app.ShortageCostEditField.Value = s
A1=c1+(h/Ed)*(r1-ED);
A2=fD*(r1*(tM-tm)*log(r1/(tM*dm))-(r1^2/dM)+(r1*tM)-
(r1*tm)*log((dM*tM)/r1)-Et);
syms x;
f=(x-r1)*fD;
EB= int(f,r1,dM*tM);
A3=Ed*f1+h*Ed*(fD*((r1^2*tm/2)-(dm*r1/2)*(tM^2-tm^2)+(dm^2/6)*
(tM^3-tm^3)-((r1^3/6*dM)-(dM*r1*tm^2/2)+(dM^2*tm^3/6)))+(fD/18)*
(tM^3-tm^3)*(dM^3-dm^3)-r1*ED+Ed*s*EB);
Q=(1/h)*((Ed*(A1+h*A2-c1)+(h*(ED-r1))));
Eoh=fD*((((r1^3*tM)/2)-(((dm*r1)/2)*(tM^2-tm^2))+(((dm^2)/6)*
(tM^3-tm^3))-((r1^3)/(6*dM))-((dM*r1*tm^2)/2)+((dM^2*tm^3)/6))+
((Q^2)/2*Ed)-(Q*ED/Ed)+((fD/(18*Ed))*((tM^3-tm^3)*(dM^3-dm^3)))+
(Q*r1/Ed)-(r1*ED/Ed));
TC= f1+c1*Q+h*Eoh+s*EB;
app.QOptimalEditField.Value = Q
app.TotalCostEditField.Value = TC
Running this gives the error:
3
I suspect the problem is with my integration process. Have I missed something or is there a better way to do this?
Thank you in advance
Regards,
Kevin Renard

Answer 1

I solved the problem as I noticed that the last error notification states that the input value must be a double scalar and the value of the integration process is not a double scalar, so I revised the integration code into:
syms x;
f=(x-r1)*fD;
EB= double(int(f,r1,dM*tM));
1