Re: How do I do very big integer computing by Mathematica?

*To*: mathgroup at smc.vnet.net*Subject*: [mg115406] Re: How do I do very big integer computing by Mathematica?*From*: Dana DeLouis <dana01 at me.com>*Date*: Mon, 10 Jan 2011 02:38:25 -0500 (EST)

On Jan 9, 2:19 am, a boy <avv... at gmail.com> wrote: > I asked how to do very-big-integer computing. For example: > Mod[2^2^64,1342352] > It's pity, this code causes overflow! > is there some funtions like this: StringMod["111...111","345=94] Hi. If I understand correctly, you're looking for the PowerMod Function. Double Check Power is Right to Left FullForm[a^b^c] Power[a,Power[b,c]] 2^3^4 == 2^(3^4) True Mod[2^2^64, 1342352] General::ovfl:Overflow occurred in computation. >> Overflow[] PowerMod[2, 2^64, 1342352] 963840 On your above =93String Version=94, here's a general idea. Let's assume n is a large number. n=123456789; Break the number (or string) into 2 or more parts. ie. {12345, 6789}; Do the first Mod: Mod[12345,345] 270 Append the results to the next number: Mod[2706789,345] 264 The results check using the original =93Large=94 number: Mod[n,345] 264 = = = = = = = Hope this Helps! Dana DeLouis Mathematica 8 on Mac Pro