Re: Multiplying a vector over multiple vectors

*To*: mathgroup at smc.vnet.net*Subject*: [mg91160] Re: [mg91150] Multiplying a vector over multiple vectors*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Fri, 8 Aug 2008 07:12:37 -0400 (EDT)*Reply-to*: hanlonr at cox.net

Map[{a, b} # &, {{1, 2}, {3, 4}, {5, 6}}] {{a, 2*b}, {3*a, 4*b}, {5*a, 6*b}} {a, b} # & /@ {{1, 2}, {3, 4}, {5, 6}} {{a, 2*b}, {3*a, 4*b}, {5*a, 6*b}} Bob Hanlon ---- Donald DuBois <donabc at comcast.net> wrote: ============= How does one get a vector to distribute over a list of vectors under multiplication? For example: {{1,2}, {3,4}, {5,6}} times {a,b} should equal (under this operation) {{a, 2b}, {3a, 4b}, {5a, 6b}} If {a,b} is duplicated three times one can use MapThread as in: MapThread[Times, {{{1, 2}, {3, 4}, {5, 6}}, {{a, b}, {a, b}, {a, b}}}] but duplicating {a,b} using Table is very slow when the vectors are large (consisting of thousands of elemets). Thanks in advance for any help you can give me. Don