MATLAB: Can’t I calculate the definite integral

definite integralMATLABsymbolicSymbolic Math Toolbox

h_min=0.5;
h_max=1.16;
pom_lc=1.21;
syms t
f=1-exp(t/pom_lc)
F=int(f, t, [h_min h_max])

answer:

f = 1 - exp((100*t)/121)
F = 33/50 - (121*exp(50/121)*(exp(6/11) - 1))/100

Why can't I calculate the integral?

F=vpa(F)

You need to index H also in your code. E.g.,

if H(k) >= 1*H_max;
    error('H too large');
elseif H(k) >= 0.9*H_max;
    Q(k) = 4 * Q_out;
        :
       etc

syms f(t)  
df = diff(f,t) ;
d2f = diff(df,t) ;
d3f = diff(d2f,t) ;
ode = d3f+df*d2f == 0 ;
cond = d2f(sym('inf')) == -1 ;
dsolve(ode,cond)