Re: expression form

*To*: mathgroup at smc.vnet.net*Subject*: [mg101008] Re: [mg100997] expression form*From*: Haibo Min <yshdfeng at gmail.com>*Date*: Sat, 20 Jun 2009 04:02:20 -0400 (EDT)*References*: <200906200048.UAA00953@smc.vnet.net>

Thank you for your time and advice, Mr. Matthias Bode. It does work in this simple case. However, It still doesn't work when the elements in vector or matrix is a little bit complicated. For example, when P={{Subscript[k, p], -Subscript[m, f] Subscript[\[Epsilon], 1], 0}, {-Subscript[m, f] Subscript[\[Epsilon], 1], Subscript[m, f], -Subscript[m, f] Subscript[\[Epsilon], 1]}, {0, -Subscript[m, f] Subscript[\[Epsilon], 1], Subscript[k, d]/b}}, and a={{Subscript[e, p]}, {Subscript[e, v]}, {\[CurlyTheta]}} Using your method: Transpose[a].P the result is still: Transpose[a].P But the weird thing is, when P is less complicated, say, P = {{Subscript[k, p], Subscript[m, f], 0}, {Subscript[m, f], Subscript[m, f], Subscript[m, f]}, {0, -Subscript[\[Epsilon], 1] Subscript[m, f], Subscript[k, d]/b}} still using Transpose[a].P or just a.P they both work! I am wondering why? Is there a specific setting command which requires the results are explicit expressions? Best regards, Haibo Min On Sat, Jun 20, 2009 at 10:10 AM, Matthias Bode <lvsaba at hotmail.com> wrote: > Hello Mr. Haibo Min: > > INPUT: > Clear[a, p] > a = {{a1}, {a2}, {a3}}; > p = {{p11, p12, p13}, {p21, p22, p23}, {p31, p32, p33}}; > Transpose[a] . p > > OUTPUT: > {{a1*p11 + a2*p21 + a3*p31, a1*p12 + a2*p22 + a3*p32, a1*p13 + a2*p23 + > a3*p33}} > > Is this the result you intended? > > Best regards, > > MATTHIAS BODE > Las Lomas de Aranjuez > COCHABAMBA/BOLIVIA > -------------------------------------------------- > From: "Haibo Min" <yshdfeng at gmail.com> > Sent: Saturday, June 20, 2009 12:48 AM > To: <mathgroup at smc.vnet.net> > Subject: [mg100997] expression form > > > 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>