rearrange data columns

Dear R users,
 I need to to the the following. Let a= 1 2 3
                                         4 5 6
 and b= -1 -2 -3  be (2x3) matrices.
        -4 -5 -6
 I need to combine the two matrices into a new (2x6) matrix like this:

 ab = ( 1 -1 2 -2 3 -3 )
        4 -4 5 -5 6 -6

 How can this be done in R?

> a
      [,1] [,2] [,3]
[1,]    1    2    3
[2,]    4    5    6
 > b
      [,1] [,2] [,3]
[1,]   -1   -2   -3
[2,]   -4   -5   -6

 > x <- cbind(a,b)+NA
 > x
      [,1] [,2] [,3] [,4] [,5] [,6]
[1,]   NA   NA   NA   NA   NA   NA
[2,]   NA   NA   NA   NA   NA   NA
 > x[,seq(from=1,by=2,len=3)] <- a
 > x[,seq(from=2,by=2,len=3)] <- b
 > x
      [,1] [,2] [,3] [,4] [,5] [,6]
[1,]    1   -1    2   -2    3   -3
[2,]    4   -4    5   -5    6   -6
 >


HTH

rksh

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