Re: coefficients of polynomial
- To: mathgroup at smc.vnet.net
- Subject: [mg107975] Re: [mg107939] coefficients of polynomial
- From: Christoph Lhotka <lhochr at gmail.com>
- Date: Thu, 4 Mar 2010 05:28:46 -0500 (EST)
- References: <201003031052.FAA20347@smc.vnet.net>
hi, try out
Block[
{equ = a x^2 + b x y + c y^2 == d (x + y)^2 + e (x - y)^2 + f (x^2 - y^2),
con = MonomialList[equ[[1]] - equ[[2]], {x, y}] /. x | y -> 1},
Solve[Thread[con == 0], {d, e, f}]
]
Christoph
Jim Armstrong wrote:
> Hi,
>
> I am trying to find the coefficients d,e,f of this simple equating:
>
> ax^2+bxy+cy^2=d(x+y)^2+e(x-y)^2+f(x^2-y^2)
>
> I mean I am waiting for this type of solution:
>
> d=(a-b+c)/2
> e=b/2
> f=(a-c)/2
>
> so how can I get these constants?
>
> I searched it and tried to use Solve, Expand...but either they dont give it or they solve it in terms of all terms (a,b,c,x,y).
>
> Thanks a lot
>
>
>
>
- References:
- coefficients of polynomial
- From: Jim Armstrong <yusufenginn@yahoo.com>
- coefficients of polynomial