Mercurial > hg > octave-terminal
changeset 12982:5e37369ea13c
polyval.m: Return zeros when polynomial is empty (ML Compatibility).
Clarify and improve syntax check.
Add Demos.
author | Ben Abbott <bpabbott@mac.com> |
---|---|
date | Mon, 22 Aug 2011 17:24:44 -0400 |
parents | 4ec4096f65d1 |
children | 8df8b402797d |
files | scripts/polynomial/polyval.m |
diffstat | 1 files changed, 29 insertions(+), 21 deletions(-) [+] |
line wrap: on
line diff
--- a/scripts/polynomial/polyval.m +++ b/scripts/polynomial/polyval.m @@ -20,7 +20,7 @@ ## @deftypefn {Function File} {@var{y} =} polyval (@var{p}, @var{x}) ## @deftypefnx {Function File} {@var{y} =} polyval (@var{p}, @var{x}, [], @var{mu}) ## Evaluate the polynomial @var{p} at the specified values of @var{x}. When -## @var{mu} is present evaluate the polynomial for +## @var{mu} is present, evaluate the polynomial for ## (@var{x}-@var{mu}(1))/@var{mu}(2). ## If @var{x} is a vector or matrix, the polynomial is evaluated for each of ## the elements of @var{x}. @@ -39,17 +39,19 @@ ## Created: June 1994 ## Adapted-By: jwe -function [y, dy] = polyval (p, x, s, mu) +function [y, dy] = polyval (p, x, s = [], mu) if (nargin < 2 || nargin > 4 || (nargout == 2 && nargin < 3)) print_usage (); endif - if (nargin < 3) - s = []; - endif - - if (! (isvector (p) || isempty (p))) + if (isempty (x)) + y = []; + return; + elseif (isempty (p)) + y = zeros (size (x)); + return; + elseif (! isvector (p)) error ("polyval: first argument must be a vector"); endif @@ -57,16 +59,6 @@ x = (x - mu(1)) / mu(2); endif - if (isempty (x)) - y = []; - return; - endif - - if (length (p) == 0) - y = p; - return; - endif - n = length (p) - 1; y = p(1) * ones (size (x)); for i = 2:n+1 @@ -80,10 +72,23 @@ ## dy = t * sqrt (1 + sumsq (A/s.R, 2)) * s.normr / sqrt (s.df) ## If my inference is correct, then t must equal 1 for polyval. ## This is because finv (0.5, n, n) = 1.0 for any n. - k = numel (x); - A = (x(:) * ones (1, n+1)) .^ (ones (k, 1) * (n:-1:0)); - dy = sqrt (1 + sumsq (A/s.R, 2)) * s.normr / sqrt (s.df); - dy = reshape (dy, size (x)); + try + k = numel (x); + A = (x(:) * ones (1, n+1)) .^ (ones (k, 1) * (n:-1:0)); + dy = sqrt (1 + sumsq (A/s.R, 2)) * s.normr / sqrt (s.df); + dy = reshape (dy, size (x)); + catch + if (isempty (s)) + error ("polyval: third input is required.") + elseif (isstruct (s) + && all (ismember ({"R", "normr", "df"}, fieldnames (s)))) + error (lasterr ()) + elseif (isstruct (s)) + error ("polyval: third input is missing the required fields."); + else + error ("polyval: third input is not a structure."); + endif + end_try_catch endif endfunction @@ -142,3 +147,6 @@ %! assert (y, polyval(p,x), eps) %! x = reshape(x, [1, 1, 5, 2]); +%!assert (zeros (1, 10), polyval ([], 1:10)) +%!assert ([], polyval (1, [])) +%!assert ([], polyval ([], []))