San (letter) San (letter) San (Ϻ) was an archaic letter of the Greek alphabet. Its shape was similar to modern M, or ϡ, or to a modern Greek Sigma (Σ) turned sideways, and it was used as an alternative to Sigma to denote the sound . Unlike Sigma, whose position in the alphabet is between Rho and Tau, San appeared between Pi and Qoppa in alphabetic order. In addition to denoting this separate archaic character, the name "San" was also used as an alternative name to denote the standard letter Sigma. The existence of the two competing letters Sigma and San is
Mu (letter) monotonic orthography, the ancient version is written with an acute accent instead of a circumflex: . The lowercase letter mu (μ) is used as a special symbol in many academic fields. Uppercase mu is not used, because it appears identical to Latin M. "μ" is conventionally used to denote certain things; however, any Greek letter or other symbol may be used freely as a variable name. In classical physics and engineering: In particle physics: In thermodynamics: In evolutionary algorithms: In type theory: In chemistry: In biology: In pharmacology: In orbital mechanics: The Olympus Corporation manufactures a series of digital cameras