empty — ([]) empty matrix
[]
denotes the empty matrix. It is uniquely defined
and has 0 row and 0 column, i.e. size([]) =[0,0]
.
The following convenient conventions are made:
[] * A = A * [] = []
[] + A = A + [] = A
[ [], A] = [A, []] = A
inv([]) =[]
det([])=cond([])=rcond([])=1, rank([])=0
Matrix functions return []
or an error message
when there is no obvious answer. Empty linear systems
( syslin
lists) may have several rows or columns.