Re: mathematica newbie question

*To*: mathgroup at smc.vnet.net*Subject*: [mg66908] Re: mathematica newbie question*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Sat, 3 Jun 2006 03:25:56 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 6/2/06 at 4:09 AM, jwatts1970 at hotmail.com (Jeremy Watts) wrote: >Just trying to get to grips with Mathematica and matrices. Why is >it when I enter :- {0, 0, 0}, {1, -1, -1}, {-1, 1, 1}}^2 >then Mathematica returns :- >{{0, 0, 0}, {1, 1, 1}, {1, 1, 1}} >and not {{0,0,0},{0,0,0},{0,0,0}} (the actual square of the matrix) >as I'd have expected? >Is it treating what I entered as separate vectors or something, and >not an actual matrix? Because by default Mathematica does an element by element multiply for expressions equivalent to a*b for matrices a,b. To get matrix multiplication you need to use ".". That is In[15]:= a={{0,0,0},{1,-1,-1},{-1,1,1}}; In[16]:= a.a Out[16]= {{0, 0, 0}, {0, 0, 0}, {0, 0, 0}} -- To reply via email subtract one hundred and four