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.
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)