Φφ
MATHEMATICS
- φ: angle/generic function; golden ratio (φ) sometimes.
- Φ: standard normal CDF (often).
PROBABILITY
- φ/Φ appear in the Normal density/CDF.
- Can also denote characteristic function (author dependent).
STATISTICS
- Φ(z): CDF of N(0,1) in tests and CIs.
- φ(z): normal density in regression/GLMs.
PRONUNCIATION
- Ancient Greek
- sound [pʰ]
- Modern Greek
- φι [fi] · sound [f]
IN FORMULAS
- Φ(z) = P(Z ≤ z)Φ is the cumulative distribution function of the standard normal.See it explained at morrisonkuhlsen.com →
- φ = (1 + √5) / 2 ≈ 1.618φ is also the golden ratio.
HOW TO WRITE IT — click to copy
lowercase
variant
uppercase
DON'T CONFUSE IT
- φ ϕ ψ θ \varphi gives the open, loopy φ; \phi gives ϕ, with a straight stroke through a closed circle.
Note: notations vary between books/fields; these are the most common usages.