MATLAB: Question about using quad function

MATLABquad

Hello, I've been trying to integrate a function (5+log(x))/(x.^2+1) using the quad function, so I input

quad('(5+log(x))/(x.^2+1)',1,4)

However, I keep getting the error

Error using quad (line 79) The integrand function must return an output vector of the same length as the input vector.

Can someone help with with this?

Notice the one additional period I added:

quad('(5+log(x))./(x.^2+1)',1,4)

1/0 is infinity, but 0/0 is not infinity nor is it zero - it's just undefined (NaN).

L = 10;
out = quad(@(z)L*z./(L/2+z).*exp(-2*z/L),0,10);