To add to what others have already pointed out, inverse square root is an important operation in finance (for example in pricing options: calculating implied volatility in Black-Scholes Model).
However, if speed is that important to you (e.g. if you are an HFT), you don't even want to be calculating the inverse square root in your hotpath. Basically, the implied volatility is "seeded" once and then you update it using greeks (finance term for a derivative, don't ask me why).
You know you're in a forum of programmers when you implicitly switch a noun from plural to singular in a parenthetical remark and instead of inferring the meaning based on context, someone feels the need to correct you.
Indeed I wasn't trying to correct the parent - I actually found the explanation pretty cool. Rather to provide some color to the folks here without financial background. I figured an explanation of what the common greeks were would help folks without a financial background understand how it's possible to work backwards from them to an updated price.
Sorry if it didn't come across that way @alex_smart!
Huh. I'm amused at the Wikipedia section on this [1].
> The use of Greek letter names is presumably by extension from the common finance terms alpha and beta, and the use of sigma (the standard deviation of logarithmic returns) and tau (time to expiry) in the Black–Scholes option pricing model. Several names such as 'vega' and 'zomma' are invented, but sound similar to Greek letters. The names 'color' and 'charm' presumably derive from the use of these terms for exotic properties of quarks in particle physics.
Who would know? Most of this stuff started off in industry rather in academia; probably somebody started writing a nu on the whiteboard sometime to mean sensitivity to implied vol and someone else gave it a Greek-sounding name that stuck.
It's before my time but I bet it's the finance equivalent of Philosophers (i.e. fashionable nonsense) science-washing their work - even if unknowingly.
However, if speed is that important to you (e.g. if you are an HFT), you don't even want to be calculating the inverse square root in your hotpath. Basically, the implied volatility is "seeded" once and then you update it using greeks (finance term for a derivative, don't ask me why).