Re: expression form

*To*: mathgroup at smc.vnet.net*Subject*: [mg101014] Re: [mg100997] expression form*From*: "Scot T. Martin" <smartin at seas.harvard.edu>*Date*: Sat, 20 Jun 2009 04:03:26 -0400 (EDT)*References*: <200906200048.UAA00953@smc.vnet.net>

I get a different result: In[1]:= a={a1,a2,a3};P={{p11,p12,p13},{p21,p22,p23},{p31,p32,p33}}; In[2]:= a.P.a Out[2]= a1 (a1 p11+a2 p21+a3 p31)+a2 (a1 p12+a2 p22+a3 p32)+a3 (a1 p13+a2 p23+a3 p33) On Fri, 19 Jun 2009, Haibo Min wrote: > 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 > > >

**References**:**expression form***From:*Haibo Min <yshdfeng@gmail.com>