empty ([]) - empty matrix

Description

[] 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.

Examples

s=poly(0,'s'); A = [s, s+1]; 
A+[], A*[]
A=rand(2,2); AA=A([],1), size(AA)
svd([])
w=ssrand(2,2,2); wr=[]*w; size(wr), w1=ss2tf(wr), size(w1)
 

See Also

matrices  poly  string  boolean  rational  syslin