Re: How to map a list on function
- To: mathgroup at smc.vnet.net
- Subject: [mg97528] Re: How to map a list on function
- From: Peter Breitfeld <phbrf at t-online.de>
- Date: Sat, 14 Mar 2009 18:15:03 -0500 (EST)
- References: <gpg18t$ceh$1@smc.vnet.net>
buts wrote: > Hello, > > Could anyone explain me how to do the following: > I have a long list of integer numbers in groups of four: > > list= {{10,3,5,7},{4,6,8,9},{0,8,3,6}, ...... } > > or its Flatten version. > > How to write a fast function g[list] which does this: > > g[list] =x^10*y^3*z^5*u^7 + x^4*y^6*z^8*u^9 + y^8*z^3*u^6+ ... > > It should be done many times (say, 10^4-6) on lists with length > 1000, so taking parts is not a good idea. > How to use Map or similar ? > Thanks. > I don't know if this is really fast, but it seems to work: list = {{10, 3, 5, 7}, {4, 6, 8, 9}, {0, 8, 3, 6}, {4, 3, 5, 9}} Plus @@ ((x^#1 + y^#2 + z^#3 + u^#4) & @@@ list) Out= 1 + u^6 + u^7 + 2 u^9 + 2 x^4 + x^10 + 2 y^3 + y^6 + y^8 + z^3 + 2 z^5 + z^8 -- _________________________________________________________________ Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de