Re: expression form

*To*: mathgroup at smc.vnet.net*Subject*: [mg101010] Re: [mg100997] expression form*From*: "David Park" <djmpark at comcast.net>*Date*: Sat, 20 Jun 2009 04:02:42 -0400 (EDT)*References*: <33011425.1245459207888.JavaMail.root@n11>

It works for me. a = {a1, a2, a3}; P = {{p11, p12, p13}, {p21, p22, p23}, {p31, p32, p33}}; a.P.a Giving... a1 (a1 p11 + a2 p21 + a3 p31) + a2 (a1 p12 + a2 p22 + a3 p32) + a3 (a1 p13 + a2 p23 + a3 p33) Copy and paste and try it again. Maybe you didn't type in the expression you thought you did. David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ From: Haibo Min [mailto:yshdfeng at gmail.com] Sent: Friday, June 19, 2009 8:48 PM Hi, I am fairly new to mathematica, and I have a question on the matrix multiplication operator. Suppose a={a1,a2,a3},P={{p11,p12,p13},{p21,p22,p23},{p31,p32,p33}}. I want to get the explicit expression of a'Pa, where a' is the transpose of vector a. Since there is no "transpose" concept for vector, my expression in mathematica is a.P.a However, it just returns {a1,a2,a3}.{{p11,p12,p13},{p21,p22,p23},{p31,p32,p33}}.{a1,a2,a3}, seems nothing is done about this, why? I use mathematica v7.0 Thank you! Haibo Min yshdfeng at gmail.com