Σ

Σ(kana Sigma) Sigma itsamba iri murugwaro rwechiGiriki iyo inomirira tsamba s. Ndiro tsamba yechi18 murugwaro rwechiGiriki. 

 Nhoroondo 
Chimiro (Σς) uye nzvimbo yearufabheti ye sigma inotorwa kubva kumashoko echiFenikiya (shin). Zita rekutanga raSigma rinogona kunge raive san, asi nekuda kwenhoroondo yakaoma yekutanga yemaGreek epicoric alphabets, san yakazozivikanwa se tsamba yakasarudzika mumavara echiGiriki, inomiririrwa se ??. 2] Herodotus anoshuma kuti "san" raiva zita rakapiwa nevaDorians kune tsamba imwechete inonzi "sigma" nevaIonians. [1] [2] Maererano neimwe fungidziro, [1] zita rekuti "sigma" rinogona kupfuurira iro reFenikiya samekh (), tsamba yakaramba ichipfuura nechiGiriki xi, inomiririrwa sa Ξ. Zvimwewo, zita racho rinogona kunge raive chiGiriki chitsva chinongoreva kuti 'kudzvova', kubva kumudzi we σίζω (sízō, kubva kuProto-Greek * sig-jō 'Ndinodzvova'). 2]

 Masvomhu 
Muzvinyorwa zvemasvomhu, σ yakaderera inowanzoshandiswa kumiririra makona asingazivikanwi, pamwe chete nekushandira sekupfupisa kwe "kuverengwa", asi Σ inowanzoshandiswa semushandi wekuwedzera, semuenzaniso.  Mukufunga kwemasvomhu,
Σ � 0 \Sigma _{n}^{0} rinoshandiswa kureva yakatarwa formulas pamwe yakaganhurirwa quantifiers kutanga pamwe kuvapo quantifiers, alternating � − 1 n-1 nguva pakati pezviitiko uye zvakapararira. Kutaura uku kunoratidza kuenzanisa kusiri pachena pakati pehukama hwekuwedzera uye zvigadzirwa kune rumwe rutivi, uye zviitiko uye zvekuenzanisa kune rumwe rutivi. Ona nyaya inotaura nezvenzira dzokuverenga nhamba. Muzviverengero, σ inomiririra chiyero chakatsauka chevanhu kana kuti kugoverwa kwemukana (apo mu kana μ inoshandiswa sechinhu chepakati). Mu topology, σ-compact topological space ndiyo inogona kunyorwa semubatanidzwa unoverengwa we compact subsets. Mukuongorora kwemasvomhu uye mufungidziro yemikana, kune rudzi rwealgebra yemaseti anozivikanwa se σ-algebra (aka σ-field). Sigma algebra inosanganisirawo mashoko akadai se: σ(A), ichiratidza iyo yakagadzirwa sigma-algebra yeseti A σ-finite measure (ona measure theory) Mune dzidziso yenhamba, σ inosanganisirwa mune akasiyana siyana ekuparadzanisa mashandiro, kunyanya sigma basa kana huwandu-hwekuparadzanisa basa. Mune applied mathematics, σ(T) inoratidza spectrum ye linear map T. Mukuongorora kwakaoma, σ inoshandiswa mu Weierstrass sigma-function. Mufungidziro yezviitiko uye nhamba, Σ inoratidza covariance matrix yeseti yezvinhu zvisingawanzoitiki, dzimwe nguva muchimiro | Σ{\displaystyle \;\displaystyle \; \! \! \Sigma } kuti iriparadzanise neoperator yekuwedzera. Theoretical spectral analysis inoshandisa σ se standard deviation inopesana ne smallcase mu se absolute mean value.