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library(Matrix)
(a <- matrix(c(2:1,1:2), 2,2))

##      [,1] [,2]
## [1,]    2    1
## [2,]    1    2

cbind(0, Matrix::rBind(a, 7)) # remains traditional matrix

## Warning: 'rBind' is deprecated.
##  Since R version 3.2.0, base's rbind() should work fine with S4 objects

##      [,1] [,2] [,3]
## [1,]    0    2    1
## [2,]    0    1    2
## [3,]    0    7    7

D <- Matrix::Diagonal(2)
Matrix::cBind(4, a, D, -1, D, 0) # a sparse Matrix

## Warning: 'cBind' is deprecated.
##  Since R version 3.2.0, base's cbind() should work fine with S4 objects

## 2 x 9 sparse Matrix of class "dgCMatrix"
##                        
## [1,] 4 2 1 1 . -1 1 . .
## [2,] 4 1 2 . 1 -1 . 1 .