qnorm
Inverse of the standard-normal cumulative distribution function.
Implements Acklam’s rational approximation (2003), accurate to about 1.15e-9 across the unit interval, including the tails. Inputs at or outside the open interval (0, 1) panic so callers do not silently receive an undefined result.
Usage
qnorm(
p,
)Parameters
| Parameter | Default | Description |
|---|---|---|
p |
Probability in the open interval (0, 1). |
Returns
Quantile z such that P(Z <= z) = p for Z ~ N(0, 1).
Examples
The 97.5th percentile is the canonical 1.96 normal quantile used in two-sided 95% intervals.
#let z = qnorm(0.975)
// z ≈ 1.96Use qnorm to derive a custom symmetric confidence multiplier for any level.
#let level = 0.99
#let mult = qnorm(0.5 + level / 2)