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Subject: Re: matrix generation
Date: Mon, 9 Nov 2009 03:55:18 +0000 (UTC)
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dpb <none@non.net> wrote in message <hd75l9$alt$2@news.eternal-september.org>...
> dpb wrote:
> > jack j wrote:
> > ...
> >> But what if the condition is something like " (1st column element-2nd
> >> column element)+(3rd column element-4th column element)"for all rows
> >> should be equal to x???
> >>
> >> In this case will such a defn work out?
> > 
> > Possibly depending on the size of the selection pool and value of x. The 
> > rudimentary case for the above would be generate three independently and 
> > solve for the fourth as the parentheses make no difference numerically 
> > to the overall sum (and since you didn't state any other condition).
> > 
> > You'll have the same problem of occasionally (or more than occasionally, 
> > perhaps) having to resample; whether that's acceptable or not on the 
> > required population statistics or not is another question you'd have to 
> > judge.
> 
> NOTA BENE:  In the above I assumed the "for all rows" means each row 
> independently satisfies the criterion.
> 
> --

Yes, each row should independently satisfy the criterion.
What happens with the following condition?
(1st column element-2nd column element)^2+(3rd column element-4th column element)^2 should be greater than x.