       • 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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