empty

Scilab Function
Last update : 25/04/2007

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` ,