Mercurial > hg > octave-lyh
diff scripts/linear-algebra/null.m @ 4371:c14ec945fabb
[project @ 2003-03-26 16:05:59 by jwe]
| author | jwe |
|---|---|
| date | Wed, 26 Mar 2003 16:05:59 +0000 |
| parents | 434790acb067 |
| children | 4c8a2e4e0717 |
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--- a/scripts/linear-algebra/null.m +++ b/scripts/linear-algebra/null.m @@ -36,30 +36,34 @@ function retval = null (A, tol) - [U, S, V] = svd (A); - - [rows, cols] = size (A); - - [S_nr, S_nc] = size (S); + if (isempty (A)) + retval = []; + else + [U, S, V] = svd (A); - if (S_nr == 1 || S_nc == 1) - s = S(1); - else - s = diag (S); - endif + [rows, cols] = size (A); + + [S_nr, S_nc] = size (S); - if (nargin == 1) - tol = max (size (A)) * s (1) * eps; - elseif (nargin != 2) - usage ("null (A, tol)"); - endif + if (S_nr == 1 || S_nc == 1) + s = S(1); + else + s = diag (S); + endif - rank = sum (s > tol); + if (nargin == 1) + tol = max (size (A)) * s (1) * eps; + elseif (nargin != 2) + usage ("null (A, tol)"); + endif - if (rank < cols) - retval = V (:, rank+1:cols); - else - retval = zeros (cols, 0); + rank = sum (s > tol); + + if (rank < cols) + retval = V (:, rank+1:cols); + else + retval = zeros (cols, 0); + endif endif endfunction