why does the fist code give me warning while the second code works well?

why does the fist code tells me minimum step size reached, while the second one give me no warnings? Thank you very much for your help.

this is the first one:

ff=@(x) 1./x ; b=quad(ff,0,1)
Warning: Minimum step size reached; singularity possible.
> In quad at 103

b =

     45.5496

here is the second one:

ff=@(x) sqrt(log(1./x)) ; b=quad(ff,0,1)

b =

      0.88621

Answer 1

[Walter Roberson]

The second one has a finite integral over that region, sqrt(pi)/2