Re: Summing elements within a List or Array

*To*: mathgroup at smc.vnet.net*Subject*: [mg69728] Re: Summing elements within a List or Array*From*: "John Adeosun" <jtadeosun at yahoo.com>*Date*: Thu, 21 Sep 2006 07:31:57 -0400 (EDT)*References*: <eebfs6$57q$1@smc.vnet.net> <eee0i8$6h0$1@smc.vnet.net>

Thanks for the useful suggestion...It works well. John. <dimmechan at yahoo.com> wrote in message news:eee0i8$6h0$1 at smc.vnet.net... > ***You can work as follows: > > In[96]:= > Flatten[Apply[Plus,alist,1],1] > Out[96]= > {0,1.2,3.5,6.9} > > ***or in compact form > > In[95]:= > Plus@@@alist//Flatten > Out[95]= > {0,1.2,3.5,6.9} > > ***As you can see in the Help Browser and also in (Ted Ersek's Tips and > Tricks) > http://www.verbeia.com/mathematica/tips/HTMLLinks/Tricks_A-K_3.html > > ***(f@@lst) is normally equivalent to Apply[f, expr] and (f@@@lst) > is normally equivalent to Apply[f, lst, 1] as demonstrated below > > In[103]:= > lst={1,2,3}; > > ln[104]:= > {Apply[f,lst]==f@@lst,Apply[f,lst,1]==f@@@lst} > Out[104]= > {True,True} > > ***BTW can you tell me how you generate your alist within Mathematica? > > > Dimitris Anagnostou > > > ÎY/Î- John Adeosun ÎÎ³Ï?Î±Ï^Îµ: >> Hello Everyone, >> >> I generated an intended list of real numbers using Mathematica 5.2, say >> "alist", that looks like: >> >> alist = {{0}, {{1.2},0}, {{2.3},{1.2},0},{{3.4},{2.3},{1.2},0}, >> ................{{99.0},{98.9},{97.8},.......,0}} >> (In Matrix form, this "alist" can be shown as a LowerDiagonal Matrix) >> >> Meanwhile, my present goal is to then program using Mathematica to obtain >> a >> list, say "aalist", having each element equal to the sum of the elements >> in >> each(corresponding) sublist of the original list "alist." That is, >> >> aalist = {0, 1.2, 3.5, 6.9,...........} >> >> In essence, it is like reducing, say, 100 by 100 matrix to 100 by 1 >> matrix >> via summing operation. >> >> I programmed using some summing operations/functions in Mathematica to >> no >> avail. I don't know what I 'm doing wrong. >> >> Can anyone help with this problem? >> >> Thanks, >> >> John. >