RE: coefficients of polynomial
- To: mathgroup at smc.vnet.net
- Subject: [mg107978] RE: [mg107939] coefficients of polynomial
- From: becko BECKO <becko565 at hotmail.com>
- Date: Thu, 4 Mar 2010 05:29:19 -0500 (EST)
- References: <201003031052.FAA20347@smc.vnet.net>
You can try something like this (i'm a beginner, so this may not the best way):
eq = a x^2 + b x y + c y^2 - d (x + y)^2 - e (x - y)^2 -
f (x^2 - y^2);
Solve[MapThread[Equal, {CoefficientList[eq, {x, y}], {
{0, 0, 0},
{0, 0, 0},
{0, 0, 0}
}}, 2] // Flatten, {d, e, f}]
> Date: Wed, 3 Mar 2010 05:52:24 -0500
> From: yusufenginn at yahoo.com
> Subject: [mg107939] coefficients of polynomial
> To: mathgroup at smc.vnet.net
>
> 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