This function will create an identity matrix, in the sparse
bdsmatrix
format.
USAGE:
bdsI(id, blocksize)
REQUIRED ARGUMENTS:
id
the identifier list.
This will become the dimnames of the final matrix, and must be a
set of unique values.
It's length determines the dimension of the final matrix
OPTIONAL ARGUMENTS:
blocksize
the blocksize vector of the final matrix.
If supplied, the sum of blocksizes must equal the dimension of the matrix.
By default, the created matrix is as sparse as possible.