MATLAB: Solve function with integration of function of variable

integralsolve

hi,

   I want to use solve function on integration of varible, but it is giving error like: 
"A and B must be floating point scalars".

The operation is like :

syms Y; solve(integral(@(x) exp(-x),0,T)==0.5);

Can you give suggestion to solve this (or) suggest me an alternative way. Thank you.

Or so :

syms x T
T0=solve(int(exp(-x),x,0,T)-0.5==0,T);

Best wishes

Torsten.

Your function is equal to

sqrt(pi)/2*(1+erf(x))

Best wishes

Torsten.

a=...;
L=...;
fun=@(x,y)(0.5*x.^3+x.^2).*exp(-x/a).*(0.5*y.^3+y.^2);
upper_y=@(x)x;
q=integral2(fun,0,L,0,upper_y);

Best wishes

Torsten.