Re: alternating sums
- To: mathgroup at CHRISTENSEN.CYBERNETICS.NET
- Subject: [mg315] Re: [mg307] alternating sums
- From: Dana_Scott at POP.CS.CMU.EDU
- Date: Mon, 12 Dec 94 08:38:51 EST
How about this definition for computing the alternating
sum of a sequence?
AS[s_] := Plus@@(s[[2 Range[(Length[s] + 1)/2]-1]]) -
Plus@@(s[[2 Range[Length[s]/2]]])
Of course the dot product with plusses and minusses is
quite easy as well.
AS2[s_] := s.Table[(-1)^i, {i,0,Length[s]-1}]