Wikipedia:Reference desk/Archives/Mathematics/2008 July 19

Mathematics desk
< July 18 << Jun | July | Aug >> July 20 >
Welcome to the Wikipedia Mathematics Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.


July 19 edit

Mod Inverse Formula edit

What is the mod inverse formula is in simple terms?--Melab-1 (talk) 18:03, 19 July 2008 (UTC)[reply]

I don't know any formula by that name, and google has nothing. Can you try to explain what formula you're talking about? Algebraist 18:20, 19 July 2008 (UTC)[reply]

Are you talking about:

 

 

where x is the inverse of 57 (mod 50)

122.107.219.245 (talk) 00:13, 20 July 2008 (UTC)[reply]

You must mean the inverse of Modulo operation?
When mod (a,b) = c,d where c=integer (a/b) d = remainder = a-(cb)
Then a = bc+a that's the nearest I can get to an inverse
If you only have c and d, then you get a range of values depending on what the divisor is.87.102.86.73 (talk) 23:33, 19 July 2008 (UTC)[reply]
Maybe Modular multiplicative inverse has what you want. PrimeHunter (talk) 00:07, 20 July 2008 (UTC)[reply]
Pretty much anything with "mod" in the name involves a loss of information, so it won't have a single-valued inverse. The best you can get is a family of inverses, like the one 87.102.86.73 mentions. We would need to know exactly what you mean by "mod" to help further, the term is used for various things. --Tango (talk) 00:21, 20 July 2008 (UTC)[reply]