If location or scale are omitted, they assume the
default values of 0 and 1 respectively. The Logistic distribution with location $= \mu$ and
scale $= \sigma$ has distribution function
$$F(x) = \frac{1}{1 + e^{-(x-\mu)/\sigma}}$$
and density
$$f(x)= \frac{1}{\sigma}\frac{e^{(x-\mu)/\sigma}}{(1 + e^{(x-\mu)/\sigma})^2}$$
The generation algorithm uses inversion. The parameters
lb and ub can be used to generate variates from
the Logistic distribution truncated to the interval (lb,ub).