Greek τ (tau) and Old Spanish x (sh) try hard in Maths

...ΤΑ ΝΕΑ: Το «τ» απειλεί το «π» του Αρχιμήδη...
...Forum. gr: Μήπως είναι λάθος το π;...
...tovima.gr/science/mathematics comment...

π (3,14...) = circumference/diameter
τ (6,28...) = circumference/radius

(wiki/Pi) Proponents of a new mathematical constant tau (τ), equal to two times π, have argued that a constant based on the ratio of a circle's circumference to its radius rather than to its diameter would be more natural and would simplify many formulae. (My conversion to Tauism, π is wrong, http://tauday.com/) While their proposals, which include celebrating 28 June as "Tau Day", have been reported in the media, they have not been reflected in the scientific literature. (bbc.co.uk/news/science-environment, wiki/Talk:Tau(2π), pi manifesto vs tau) 

Pi (π) symbol originates from the words periphery or perimeter. What does tau mean?  I guess τομή, intersection, incision, ratio....or Turn (geometry)....hm, one-legged τ resembles two-legged π...so, 2π would suit far better to be symbolized with two-pied m, which is also the italic lowercase form of cyrillic Te.

Let's see another viral, variously e-circulated, math-letter....

http://www.ted.com/talks/lang/el/terry_moore_why_is_x_the_unknown.html http://www.ted.com/speakers/terry_moore.html —I was told that the Arabic mathematicians used to put شيء 'something' as a variable. How a variable would be represented in Arabic? —Indeed, we use shin letter س as a variable (in maths, physics and chemistry). http://forum.wordreference.com/showthread

According to the Oxford English Dictionary (2nd ed.):

"There is no evidence in support of the hypothesis that the variable x is derived ultimately from the mediaeval transliteration xei of shei "thing", used by the Arabs to denote the unknown quantity, or from the compendium for L. res "thing" or radix "root" (resembling a loosely-written x), used by mediaeval mathematicians." (wiki/X) In mathematics, x is commonly used as the name for an independent variable or unknown value. While it is widely believed that the usage of x to represent an independent or unknown variable can be traced back to the Arabic word šay' شيء = “thing”, there are no sources to support this claim. Modern tradition of using x to represent unknowns was started by Rene Descartes in his La geometrie, 1637. (Source: A History of Mathematical Notations by Florian Cajori)

In Medieval Spanish

/ʃ/: was represented by the letter ⟨x⟩ (pronounced like the English digraph ⟨sh⟩

e.g. old: dexar (ʃ), modern: dejar (x), portuguese: deixar (ʃ) old sp./port: oxalá, modern sp: ojalá (cf. arabic inshallah)

άηχο υπερωικό τριβόμενο (voiceless velar fricative, ' x ' ) χαρά, χώμα, spanish ojo

άηχο ουρανικό τριβόμενο (voiceless palatal fricative, ' ç ' )  χιόνι, χέρι, english hue

άηχο παχύ συριστικό τριβόμενο (voiceless palato-alveolar sibilant, ' ʃ '  ) 

share, shampoo, ship

X was pronounced [ʃ], as it is still currently in other languages of Iberia, Portuguese, Galician, Asturian, Catalan and Basque. Later, the sound evolved to a hard [x] sound. In modern Spanish, the hard [x] sound is spelled with a j, (e.g. reloj)  or with a g before e and i, (e.g. gente, giro), though x is still retained for some names (e.g. México/Mejico, Oaxaca/Oajaca, Xerez/Jerez). Now, X represents the sound [s] (word-initially e.g. in greek words as xilófono (silófono) and xenofobia (senofobia), or the consonant cluster [ks] (e.g. oxígeno, examen). Even more rarely, the x can be pronounced [ʃ] as in Old Spanish in some proper nouns such as Raxel (a variant of Rachel), Uxmal (Mayan city).

Non-Iberian Romance languages sharing also the consonant /ʃ/: French: chat > cattus, Italian: uscire > exire, Romanian: șarpe > serpens. Palatalization was one of the most important processes affecting consonants in Vulgar Latin. Το βίντεο γνώρισα από σχόλιο στου Σαραντάκου σε μαθηματική συζήτηση, και έτσι θυμήθηκα και ένα παλιότερο από την ανάρτηση για το εξάξω:  "Τόσα ξι μαζεμένα δεν είχαν ούτε οι προκολομβιανοί πολιτισμοί της Ν. Αμερικής". Όλα αυτα τα x, λοιπόν, στα μεσοαμερικάνικα τοπωνύμια προφέρονται ʃ στην τοπική γλώσσα και x στα ισπανικά, όπως την Οαχάκα, που γνωρίσαμε από τους ζαπατίστας. Την αρχαία προφορά του x ως sh, είχαμε δεί και παλιότερα στα σεφαραδίτικα, Porque llorax Blanca Nina?  Ώστε, πως κάποτε στο μεσαίωνα οι ισπανοί, που είχαν ήδη  x (sh), δανείστηκαν το ελληνικό χ για να αποδώσουν το αράβικο shin, μόνο ως χιουμοριστικό ανέκδοτο μπορεί να ακουστεί. Αν τύχαινε, πάντως, σε Κύπριους ή Κρητικούς να μεταγράψουν την άγνωστη μεταβλητή του shin, έτσι ακριβώς, όπως οι Ισπανοί, θα επέλεγαν το χι με το ʃέριν και τη ʃέρα στην καρδιά :-). Ενώ οι υπόλοιποι Έλληνες θα έβαζαν το σ ή ς, δεν λένε προφίσιενσυ αντί για προφίχιενσυ;-)...μα και οι Άγγλοι το s από το something, που λέει στο βίντεο, από τη στιγμή που έπρεπε να αποδοθεί με ένα μόνο γράμμα.

So, x is wrong! s is right! 

let a new campaign arise

.......  P.S. Ιt is also noteworthy that "xenos", ξένος, is the Greek word for unknown, stranger, guest, or foreigner, and that might explain the reasons Europeans used the letter x to denote the "unknown” in algebraic equations.  (Dr. Ali Khounsary Δρ Αλι Χουνσαρυ)