[R] Linear system

[Arne Henningsen]

On Wednesday 25 May 2005 14:30, Jim Gustafsson wrote:
> Dear R-help
>
> I have a problem solving a linear system like
>
> 353a+45b+29c=79
> 45a+29b+3c=5
> 29a+3b+4c=8
>
> Is there any way of doing this in R?


You can write this equation system in matrix form:
M * x = y

with 
x = ( a, b, c )
M = ( 353, 45, 29,
       45, 29,  3,
       29,  3,  4 )
y = ( 79, 5, 8 )

you can solve the system by 
x = M^(-1) * y

In R you can do this by
R> M = matrix( c( 353, 45, 29, 45, 29,  3, 29,  3,  4 ), 
   ncol = 3, byrow = TRUE )
R> y <- c( 79, 5, 8 )
R> x <- solve( M ) %*% y 
or
R> x <- solve( M, y )

Please read a basic book about linear algebra.

Arne


> Best Regards
> Jim
>
>
> ---------------------------------------------------------------------------
>--- This e-mail and any attachment may be confidential and may also be
> privileged. If you are not the intended recipient, please notify us
> immediately and then delete this e-mail and any attachment without
> retaining copies or disclosing the contents thereof to any other person.
> Thank you.
> ---------------------------------------------------------------------------
>--- [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html

-- 
Arne Henningsen
Department of Agricultural Economics
University of Kiel
Olshausenstr. 40
D-24098 Kiel (Germany)
Tel: +49-431-880 4445
Fax: +49-431-880 1397
ahenningsen at agric-econ.uni-kiel.de
http://www.uni-kiel.de/agrarpol/ahenningsen/