Re: how to sum lists of unequal length?

*To*: mathgroup at smc.vnet.net*Subject*: [mg70381] Re: [mg70352] how to sum lists of unequal length?*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Sun, 15 Oct 2006 00:18:43 -0400 (EDT)*References*: <200610140706.DAA07887@smc.vnet.net>

On 14 Oct 2006, at 16:06, Arkadiusz.Majka at gmail.com wrote: > Hi all, > > I have lists of unknown and unequal lengths. I want to sum them, e.g > > {a1,a2,a3}+{b1,b2,b3,b4,b5} and obtain result > {a1+b1,a2+b2,a3+b3,b4,b5}. Simply filling by zeros of the shorter list > is impossible because I have no idea how many zeros I have to pad. > > Please, help > > Arek > One way: AddLists[l_,m_]:=With[{ p=Max[Length[l],Length[m]]},PadRight[l,p]+PadRight[m,p]] AddLists[{a1,a2,a3},{b1,b2,b3,b4,b5}] {a1+b1,a2+b2,a3+b3,b4,b5} Andrzej Kozlowski Tokyo, Japan

**References**:**how to sum lists of unequal length?***From:*Arkadiusz.Majka@gmail.com