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From: NZTideMan <mulgor@gmail.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Cramer's Rule - linear equations
Date: Wed, 14 May 2008 00:21:45 -0700 (PDT)
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On May 14, 12:54=A0pm, "Roger Stafford"
<ellieandrogerxy...@mindspring.com.invalid> wrote:
> "Ashwini Deshpande" <vd.ashw...@mathworks.com> wrote in message
>
> <g0bdna$rj...@fred.mathworks.com>...> I have three linear equations with 3=
 unknowns, say for example:
>
> > 3x + 4y + 6z =3D 1;
> > x - 2y + 7z =3D 10;
> > 2x + 3y - 9z =3D 15;
>
> > How do i solve this using matlab, is there any easiest way
> > to apply Cramer's Rule to Solve these equations ???
>
> > Any help would be appreciated !!
> > Thanks !
> > Ashwini
>
> -------------
> =A0 It is true that using Cramer's Rule in matlab would in general constit=
ute an
> inefficient method of solving linear equations, when there are so many
> superior algorithms available. =A0However, it must be said in defense of
> Cramer's Rule that it remains a very useful tool in mathematics, both in
> understanding the theory in linear algebra and also for doing certain symb=
olic
> manipulations. =A0I personally have to resort to its use quite often in de=
riving
> various formulas and the like. =A0It is only in the area of actual numeric=
al
> computation that other methods become preferable.
>
> Roger Stafford

I agree entirely with you Roger, but the OP quoted a numerical
example, not a symbolic one.

How large a matrix would you use Cramer's Rule on?  Back when I learnt
it and access to computers was difficult (i.e., Hollerith cards
submitted as a background job) I could handle 3x3 no trouble and 4x4
with a bit of effort, but these days 2x2 would be my limit before
finding a better way.