[R] RE : Help to solve matrices

[Marc Schwartz]

Justin,

Did you actually run that code?  :-)

> a<-array(c(3,4,1),dim=c(3,1))
> b<-a%*%a
Error in a %*% a : non-conformable arguments

I suspect that Amina wants:

a <- array(c(3, 4, 1), dim=c(3, 1))
b <- t(a) %*% a

> solve(b)
           [,1]
[1,] 0.03846154


or perhaps:

> solve(crossprod(a))
           [,1]
[1,] 0.03846154


Amina, note that %o% is an 'outer' product, not an 'inner' product.

See ?outer and ?"%*%"

HTH,

Marc Schwartz


On Wed, 2007-01-31 at 20:21 +0100, justin bem wrote:
> >a<-array(c(3,4,1),dim=c(3,1))
> >b<-a%*%a
> >solve(b)
> 
> amna khan <amnakhan493 at gmail.com> a crit : Sir I am new user of R. I
> am facing problems in solving matrices.
> for example
> >a<-array(c(3,4,1),dim=c(3,1))
> >b<-a%o%a
> >b
> 
> , , 1, 1
> 
>      [,1]
> [1,]    9
> [2,]   12
> [3,]    3
> 
> , , 2, 1
> 
>      [,1]
> [1,]   12
> [2,]   16
> [3,]    4
> 
> , , 3, 1
> 
>      [,1]
> [1,]    3
> [2,]    4
> [3,]    1
> >solve(b)
> Error in solve.default(b) : only square matrices can be inverted
> >solve(b,a)
> Error in solve.default(b, a) : 'b' must be compatible with 'a'
> Sir I request you to help me in  this regard.