gaussPhi is the standard normal CDF #
GeluErf writes the density and the CDF in closed form over the interval integral, so the
modules that import the exact GELU do not carry the probability library. This file ties both to
Mathlib's Gaussian:
gaussPdf_eq_gaussianPDFReal:gaussPdfisgaussianPDFReal 0 1.gaussPhi_eq_measureReal_Iic,gaussPhi_eq_cdf:gaussPhi xis the mass the standard normalgaussianReal 0 1gives(−∞, x], i.e. itscdf.
The ½ in gaussPhi's definition is integral_Iic_zero_gaussPdf: the density is even and
integrates to one.
gaussPdf is Mathlib's Gaussian density at mean 0, variance 1.
gaussPdf is integrable over the line.
gaussPhi is the standard normal's mass on (−∞, x].
gaussPhi is the CDF of the standard normal, as Mathlib defines both.