### def f(x): evaluvates individually but not inside plot

Hi,
I am stuck with a curious error.
The code to reproduce error is given below.
The function T basically integrates the function with a given value of L.

```
def T(L): return n(integral(4/sqrt(pi)*exp(-L)*(x^2)*exp(-x^2/4)/cosh(sqrt(L)*x),x,0,+Infinity))
plot(T,5,7)
```

The function T works fine if I ask

```
print T(5)
```

But it gives error, when i give the above mentioned plot command.
What might be going wrong here?