zs
Z-S decomposition of a matrix.
[Z,T]=zs(A)
Inputs
A A real matrix of size nXm with m>=n .
Outputs
Z A unitary matrix of size mXm .
T A right upper triangular matrix of size nXm .


Description
The results satisfy A*Z=T . Note also that for m>n , T is of the form [0 S] , where S is an upper triangular square matrix of size m .
Example
>>a=[1 2 3 4;5 6 7 8;9 10 11 12]
>>a
          1          2          3          4
          5          6          7          8
          9         10         11         12

>>[z,s]=zs(a)
>>z
   -0.2806    0.4704   -0.7200   -0.4262
    0.7247   -0.4181   -0.2753   -0.4735
   -0.6077   -0.5750    0.1694   -0.5209
    0.1636    0.5227    0.6141   -0.5682

>>s
         0         0    1.6941   -5.2087
         0         0    0.8470  -13.1637
         0         0         0  -21.1187
>>z*z'
    1.0000         0         0         0
         0    1.0000         0         0
         0         0    1.0000         0
         0         0         0    1.0000

>>norm(a*z-s)
      3.6637e-015