# 希腊24字母表（发音）

2019年10月8日 / 69次阅读

• $\alpha$ (lower case alpha) – a generic variable; an angle of a triangle
• $\beta$ (lower case beta) – a generic variable; a different angle of a triangle
• $\Gamma$ (capital gamma) – the gamma function; the graph of a function as a set of pairs; a graph in the sense of graph theory
• $\gamma$ (lower case gamma) – a closed curve (e.g., integrating over the real or complex plane)
• $\Delta$ (capital delta) – a change; the max degree of a graph
• $\delta$ (lower case delta) – a change; a small positive value that you may choose; an impulse
• $\varepsilon$ (lower case epsilon) – a small arbitrary positive real number; an error rate
• $\zeta$ (lower case zeta) – the Riemann zeta function; a complex variable (like z)
• $\eta$ (lower case eta) – an error rate; a step size in an algorithm
• $\Theta$ (capital theta) – an angle; asymptotic equivalence
• $\theta$ (lower case theta) – an angle
• $\iota$ (lower case iota) – the inclusion function; an injective function or embedding
• $\kappa$ (lower case kappa) – curvature; connectivity; conditioning
• $\Lambda$ (capital lambda) – matrix of eigenvalues
• $\lambda$ (lower case lambda) – an eigenvalue of a matrix
• $\mu$ (lower case mu) – a measure; a mean;
• $\nu$ (lower case nu) – None. I hate this letter because I think it’s hard to draw and it’s too close to v.
• $\Xi$ (capital xi, like “ksee”) – None. It’s a weird letter that only a math troll would love. Too close to $\equiv$ and conflicts with drawing bars on top of variables.
• $\xi$ (lower case xi) – a complex variable; I often draw it like a lightning bolt with a hat.
• $\Pi$ (capital pi) – a product;
• $\pi$ (lower case pi) – the constant~3.14; a projection
• $\rho$ – projection; a rate; a rotation; a correlation
• $\Sigma$ (upper case sigma) – sum; an alphabet of symbols; covariance matrix
• $\sigma$ (lower case sigma) – standard deviation; a symmetry; a reflection; a sign +/-1.
• $\tau$ (lower case tau) – a symmetry; a translation; if I really want to use $\pi$ but it would be confusing, so I draw it standing like a bird holding up one of its legs.
• $\Upsilon$ (capital upsilon) – ??
• $\upsilon$ (lower case upsilon) – Too close to “u,v” not used.
• $\Phi$ (capital phi, like “fai”, though many pronounce “fee”) – a general function; a potential function
• $\phi$ or $\varphi$ (lower case phi) – a function/morphism; golden ratio; totient function
• $\chi$ (lower case chi, like “kai”) – a character; a statistic; the indicator function of an event; Euler characteristic
• $\Psi$ (capital psi, like “sai”) – a function/morphism;
• $\psi$ (lower case psi) – a function/morphism
• $\Omega$ (capital omega) – a lower bound
• $\omega$ (lower case omega) – a lower bound; a complex cube root of 1

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