dsolve - Unable to find implicit solution

>> syms y(t)
>> eqn = diff(y) == y+exp(-y)
 
eqn(t) =
 
diff(y(t), t) == exp(-y(t)) + y(t)
 
>> sol = dsolve(eqn)
Warning: Unable to find explicit solution. Returning implicit
solution instead. 
> In dsolve (line 197) 
 
sol =
 
lambertw(0, -1)
 
>> sol = dsolve(eqn,'Implicit',true)
Error using char
Conversion to char from logical is not possible.

Error in dsolve>mupadDsolve (line 274)
if isvarname(char(args{end}))

Error in dsolve (line 183)
sol = mupadDsolve(args, options);
 

[Walter Roberson]

Which release are you using? When I dsolve() I do not get the warning for the first case, and the second case does not give me an error (but the result is a bit odd)

Answer 1

[Star Strider]

That is not very illumiunating.

Try this:

syms y(t) T Y 
eqn = diff(y) == y+exp(-y);
[VF,Subs] = odeToVectorField(eqn);
eqnfcn = matlabFunction(VF, 'Vars',{T,Y});

[t,y] = ode45(eqnfcn, [0 1], 1);

figure
plot(t, y)
grid

Choose appropriate values for the time interval ([0 1] here) and initial condition (here 1).