RE: help for time series basic operations

*To*: mathgroup at smc.vnet.net*Subject*: [mg46054] RE: [mg46046] help for time series basic operations*From*: "David Park" <djmp at earthlink.net>*Date*: Tue, 3 Feb 2004 22:19:07 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Paolo, Use RotateLeft, subtract and Drop the last item. (% is the output from the previously evaluated statement. If you put a number of statements together in one cell it's safe to use.) timeseries = Table[a[i], {i, 1, 10}] RotateLeft[timeseries] % - timeseries Drop[%, -1] Or wrapping it all in one statement... Drop[RotateLeft[timeseries] - timeseries, -1] David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: paolo [mailto:tarpanelli at libero.it] To: mathgroup at smc.vnet.net I am a quantitative analyst and for the first time i am using Mathematica. So, I am sorry if my question seem "very easy (almost stupid)" but i need some helps to begin to understand Mathematica I have a time series a:=[a_1,a_2,a_3,a_4,...a_n] how can i do to subtract each element for the previous one?: b:=[a_2 - a_1, a_3 - a_2, a_4 - a_3,.....,a_n - a_n-1] Thanks Paolo Tarpanelli