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Re: please solve
*To*: mathgroup at smc.vnet.net
*Subject*: [mg52998] Re: please solve
*From*: rcmcll at yahoo.com
*Date*: Sun, 19 Dec 2004 06:14:43 -0500 (EST)
*References*: <cprk0m$r87$1@smc.vnet.net><cpuh1i$gui$1@smc.vnet.net>
*Sender*: owner-wri-mathgroup at wolfram.com
Maybe I should define t. t is just time 1,2,3..,n and t^2 is
1,4,9,...n^2 like that.
I didn't think about singularity as this is a simple regression problem
that works when one uses actual values. I'm trying to get simple
formulas for beta instead of the usual ones.Sorry about that. Maybe I
can take usual formulas and try to get a simple solution thru that.
Thanks for all the effort
Bob
Robert M. Mazo wrote:
> On Thu, 16 Dec 2004 09:20:22 +0000 (UTC), rcmcll at yahoo.com wrote:
>
> >Greetings:
> >
> >Could someone please solve this symbolically?
> >This is just the ols formula for beta-hat but I need a symbolic
> >solution for this special case.
> >
> >b = inv(x'x)x'y
> >
> >where
> >
> >x = 1 t t^2
> >1 t t^2
> >1 t t^2
> >
> >
> >and simplify simplify simplify!!
> >
> >Thanks,
> >
> >Bob
>
> If I understand the notation, x is a matrix. Yes? If so, x is
> singular and doesn't have an inverse. Hence neither does x'x, so the
> problem has no solution. Or, better put, the problem is ill posed.
>
> A dsifferent Bob
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