let $f(t)=t$ be an analytic function which has a fixed-point at $t$. The multiplier $\lambda (t) = f'(t)$ is just the 1st derivative evaluated at the fixed-point. The standard nomenclature is that when $\| \lambda (t) \|=1$ the fixed-point is said to be indifferent, or neutral. However, it does not necessarily mean that trajectories can't be attracted or repelled by this point, only that its 1st derivative equals 1.
Wouldn't "indeterminate" be a better name than "indifferent" ?
The function $(1 / ( 1 - \| \lambda (t) \| ) )$ is ill-defined when $\lambda(t) = 1$