Re: Variable number of arguments

*To*: mathgroup at smc.vnet.net*Subject*: [mg113342] Re: Variable number of arguments*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 24 Oct 2010 06:06:15 -0400 (EDT)

It's not clear what you want done if the multiple elements are themselves lists or the arguments are a mix of lists and individual elements. The following approach will sum all the individual elements no matter how they are structured. funnySum1[x__] := Plus @@ Flatten[{x}] {funnySum1[1, 2, 3, 4], funnySum1[{1, 2, 3, 4}], funnySum1[1, 2, {3, 4}], funnySum1[{1, 2}, {3, 4}], funnySum1[{{1, 2}, {3, 4}}]} {10, 10, 10, 10, 10} funnySum2[x__] := Total[Flatten[{x}]] {funnySum2[1, 2, 3, 4], funnySum2[{1, 2, 3, 4}], funnySum2[1, 2, {3, 4}], funnySum2[{1, 2}, {3, 4}], funnySum2[{{1, 2}, {3, 4}}]} {10, 10, 10, 10, 10} funnySum3[x__] := Tr[Flatten[{x}]] {funnySum3[1, 2, 3, 4], funnySum3[{1, 2, 3, 4}], funnySum3[1, 2, {3, 4}], funnySum3[{1, 2}, {3, 4}], funnySum3[{{1, 2}, {3, 4}}]} {10, 10, 10, 10, 10} Bob Hanlon ---- Sam Takoy <sam.takoy at yahoo.com> wrote: ============= Hi, I'm looking for help writing functions with variable number of arguments. For example, how do I accomplish the (rather artificial) task of writing the function FunnySum that: - When called with multiple arguments, sums them - When called with a list, sums the elements of the list I was hoping that the FunnySum1 below would work, but it doesn't multiple arguments. FunnySum2 works, but is that the best solution? FunnySum1[k__] := Apply[Plus, If[ListQ[k], Sequence[k], k]] FunnySum1[{1, 2, 3, 4, 5, 6}] FunnySum2[k__] := Plus[k] FunnySum2[k_List] := Apply[Plus, Sequence[k]] FunnySum2[1, 2, 3, 4, 5, 6] FunnySum2[{1, 2, 3, 4, 5, 6}] Many thanks in advance, Sam