RE: help for time series basic operations

*To*: mathgroup at smc.vnet.net*Subject*: [mg46061] RE: [mg46046] help for time series basic operations*From*: "John C. Erb, Ph.D." <John_C_Erb at prodigy.net>*Date*: Wed, 4 Feb 2004 02:29:31 -0500 (EST)*Reply-to*: <John_C_Erb at prodigy.net>*Sender*: owner-wri-mathgroup at wolfram.com

I'm sure there are more "elegant" ways, but a Do loop works fine Example this={a1,a2,a3,a4,a5}; that=Table[0,{i,Length[this]-1}]; Do[ that[[i]]=this[[2]]-this[[1]]; this=Drop[this,1];, {i,Length[that]}]; that John C. Erb Email: John_C_Erb at prodigy.net -----Original Message----- From: paolo [mailto:tarpanelli at libero.it] To: mathgroup at smc.vnet.net Subject: [mg46061] [mg46046] help for time series basic operations 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