Re: Multiplying a vector over multiple vectors

*To*: mathgroup at smc.vnet.net*Subject*: [mg91162] Re: Multiplying a vector over multiple vectors*From*: "David Park" <djmpark at comcast.net>*Date*: Fri, 8 Aug 2008 07:12:59 -0400 (EDT)*References*: <g7ed6u$2pm$1@smc.vnet.net>

testmatrix = {{1, 2}, {3, 4}, {5, 6}}; {a, b} # & /@ testmatrix {{a, 2 b}, {3 a, 4 b}, {5 a, 6 b}} First@Outer[Times, {a, b}, testmatrix] {{a, 2 a}, {3 a, 4 a}, {5 a, 6 a}} -- David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ "Donald DuBois" <donabc at comcast.net> wrote in message news:g7ed6u$2pm$1 at smc.vnet.net... > 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 >