exp(40) > 10^17 Thus, if x >= 1, for x + exp(-40) all significant bits of the exponential are lost and the result is identical to just saying x. Likewise for x <=1, for 1+exp(40), the addition of 1 has no effect.
The logistic function [1] is defined as f(x) = 1 / (1 + exp(-x)), thus when using double precision floating point where x >= 40, f(x) = 1 and where x <= -40, f(x) = 0. [1] https://en.wikipedia.org/wiki/Logistic_function On Fri, May 23, 2014 at 4:23 AM, namit maheshwari < [email protected]> wrote: > Hello Everyone, > > In mahout's *AbstractOnlineLogisticRegression *class the *public static > Vector link(Vector v)* > function checks the *max* value against 40. > > Could anyone please explain the significance of 40 in context of Logistic > Regression? > > Thanks > Namit >
