quantile
The metalog quantile function evaluated in fitting space, parameterized by the logit of the cumulative probability rather than by the probability itself.
This reaches much further into the tails than the probability-based overload can. Near one, consecutive doubles are about a tenth of a quadrillionth apart, so a probability handed in as a double has already lost the information needed to recover its own logit: at a logit of thirty the round trip is wrong in the third decimal place. Parameterizing by the logit avoids the loss entirely, since the logit is then exact and the centered probability is obtained from the hyperbolic tangent of half of it, which does not cancel.
Use this wherever the far tail matters, such as integrating a moment of a semi-bounded metalog whose quantile function grows like a power law.