Mercurial > hg > octave-max
changeset 11476:ff7e0776ba0f
logm.m: handle scalar and diagonal matrix arguments specially; call log_pade_pf only if m > 1
| author | John W. Eaton <jwe@octave.org> |
|---|---|
| date | Mon, 10 Jan 2011 14:48:55 -0500 |
| parents | caf1fd72f587 |
| children | a02d00dd3d5f |
| files | scripts/ChangeLog scripts/linear-algebra/logm.m |
| diffstat | 2 files changed, 23 insertions(+), 1 deletions(-) [+] |
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--- a/scripts/ChangeLog +++ b/scripts/ChangeLog @@ -1,3 +1,9 @@ +2011-01-10 John W. Eaton <jwe@octave.org> + + * linear-algebra/logm.m: Handle scalar and diagonal matrix + arguments specially. Call logm_pade_pf only if m > 1. New tests. + Special case suggested by Marco Caliari <marco.caliari@univr.it>. + 2011-01-10 John W. Eaton <jwe@octave.org> * general/private/__isequal__.m: Use builtin ("struct", ...) to
--- a/scripts/linear-algebra/logm.m +++ b/scripts/linear-algebra/logm.m @@ -49,6 +49,14 @@ error ("logm: A must be a square matrix"); endif + if (isscalar (A)) + s = log (A); + return; + elseif (strfind (typeinfo (A), "diagonal matrix")) + s = diag (log (diag (A))); + return; + endif + [u, s] = schur (A); if (isreal (A)) @@ -84,7 +92,11 @@ warning ("logm: maximum number of square roots exceeded; results may still be accurate"); endif - s = logm_pade_pf (s - eye (size (s)), m); + s = s - eye (size (s)); + + if (m > 1) + s = logm_pade_pf (s, m); + endif s = 2^k * u * s * u'; @@ -144,3 +156,7 @@ %!error logm (); %!error logm (1, 2, 3); %!error <logm: A must be a square matrix> logm([1 0;0 1; 2 2]); + +%!assert (logm (10), log (10)) +%!assert (full (logm (eye (3))), logm (full (eye (3)))) +%!assert (full (logm (10*eye (3))), logm (full (10*eye (3))), 8*eps)