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