Re: help for time series basic operations

*To*: mathgroup at smc.vnet.net*Subject*: [mg46081] Re: [mg46046] help for time series basic operations*From*: Hugh Walker <hwalker at gvtc.com>*Date*: Thu, 5 Feb 2004 04:03:00 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

On Tuesday, February 3, 2004, at 05:20 PM, paolo wrote: > 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 Paolo: Here is one way. Let lst be the list in question, then the "difference list" is lstSub = Drop[(RotateLeft[lst] - lst), -1] Cheers, ========== Hugh Walker Gnarly Oaks