Re: Find the derised results
- To: mathgroup at smc.vnet.net
- Subject: [mg123693] Re: Find the derised results
- From: Bob Hanlon <hanlonr357 at gmail.com>
- Date: Fri, 16 Dec 2011 05:42:03 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201112150956.EAA23039@smc.vnet.net>
expr = {x, y, z,
t}.{{x1, y1, z1, t1}, {x2, y2, z2, t2}, {x3, y3, z3, t3}, {x4, y4,
z4, t4}}.{x, y, z, t}
t (t t4 + t1 x + t2 y + t3 z) + x (x x1 + t x4 + x2 y + x3 z) +
y (x y1 + y y2 + t y4 + y3 z) + z (x z1 + y z2 + z z3 + t z4)
Coefficient[expr, x1] x1
x^2*x1
x1*CoefficientList[expr, x1] // Rest
{x^2*x1}
Cases[expr // Expand, _*x1]
{x^2*x1}
Select[expr // Expand, MemberQ[#, x1] &]
x^2*x1
Cases[expr // Expand, _?(MemberQ[#, x1] &)]
{x^2*x1}
Select[expr // Expand, ! FreeQ[#, x1] &]
x^2*x1
Cases[expr // Expand, _?(! FreeQ[#, x1] &)]
{x^2*x1}
Bob Hanlon
On Thu, Dec 15, 2011 at 4:56 AM, =E9=81=93 =E5=8E=9A <shlwell1988 at gmail.com> wrote:
> {x,y,z,t}.{{x1,y1,z1,t1},{x2,y2,z2,t2},{x3,y3,z3,t3},{x4,y4,z4,t4}}.
> {x,y,z,t}
>
> How can I find those terms with x1 in the above result by some
> different methods?
>
- References:
- Find the derised results
- From: é å <shlwell1988@gmail.com>
- Find the derised results