χ is the 22nd Greek letter, and its lowercase letter is χ, which usually means that there is a chi-square (χ 2) distribution statistically. ψ is the 23rd Greek letter, and its lowercase letter is ψ, which usually refers to angular velocity, dielectric electric flux, ψ function and magnetic flux.
Extended data:
The pronunciation of common Greek letters is as follows:
1, alpha, lowercase alpha, English name is alpha, English phonetic notation is/'? What if? /,the Chinese name is alpha.
2, beta, lowercase beta, English name is beta, English phonetic notation is /'bi:t? /or/'Really? t？ /,Chinese name is Beta.
3.γ, lowercase γ, English name is gamma, and English phonetic notation is /'g? m？ /,Chinese name is Gamma.
4, δ, lowercase δ, the English name is delta, and the English phonetic notation is /'delt? /,the Chinese name is Delta.
5, ∧, lowercase λ, English name is lambda, and English phonetic notation is /'l? md？ /,Chinese name is Ramda.
Baidu Encyclopedia-Greek alphabet