Mercurial > hg > octave-lyh
annotate scripts/polynomial/polyderiv.m @ 11100:cdf940db26a0
provide mxIsFunctionHandle MEX interface function
| author | John W. Eaton <jwe@octave.org> |
|---|---|
| date | Sat, 16 Oct 2010 13:27:18 -0400 |
| parents | a8ce6bdecce5 |
| children | c776f063fefe |
| rev | line source |
|---|---|
| 7017 | 1 ## Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2004, |
| 8920 | 2 ## 2005, 2006, 2007, 2008 John W. Eaton |
| 2313 | 3 ## |
| 4 ## This file is part of Octave. | |
| 5 ## | |
| 6 ## Octave is free software; you can redistribute it and/or modify it | |
| 7 ## under the terms of the GNU General Public License as published by | |
| 7016 | 8 ## the Free Software Foundation; either version 3 of the License, or (at |
| 9 ## your option) any later version. | |
| 2313 | 10 ## |
| 11 ## Octave is distributed in the hope that it will be useful, but | |
| 12 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 14 ## General Public License for more details. | |
| 15 ## | |
| 16 ## You should have received a copy of the GNU General Public License | |
| 7016 | 17 ## along with Octave; see the file COPYING. If not, see |
| 18 ## <http://www.gnu.org/licenses/>. | |
| 904 | 19 |
| 3368 | 20 ## -*- texinfo -*- |
|
10687
a8ce6bdecce5
Improve documentation strings.
Rik <octave@nomad.inbox5.com>
parents:
10549
diff
changeset
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21 ## @deftypefn {Function File} {} polyderiv (@var{c}) |
| 6850 | 22 ## @deftypefnx {Function File} {[@var{q}] =} polyderiv (@var{b}, @var{a}) |
| 23 ## @deftypefnx {Function File} {[@var{q}, @var{r}] =} polyderiv (@var{b}, @var{a}) | |
| 3368 | 24 ## Return the coefficients of the derivative of the polynomial whose |
| 5216 | 25 ## coefficients are given by vector @var{c}. If a pair of polynomials |
| 26 ## is given @var{b} and @var{a}, the derivative of the product is | |
| 27 ## returned in @var{q}, or the quotient numerator in @var{q} and the | |
| 28 ## quotient denominator in @var{r}. | |
|
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point to polyint in @seealso, not polyinteg
John W. Eaton <jwe@octave.org>
parents:
8920
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changeset
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29 ## @seealso{poly, polyint, polyreduce, roots, conv, deconv, residue, |
| 5642 | 30 ## filter, polygcd, polyval, polyvalm} |
| 3368 | 31 ## @end deftypefn |
| 1025 | 32 |
| 3202 | 33 ## Author: Tony Richardson <arichard@stark.cc.oh.us> |
| 2312 | 34 ## Created: June 1994 |
| 35 ## Adapted-By: jwe | |
| 561 | 36 |
| 5216 | 37 function [q, r] = polyderiv (p, a) |
| 38 | |
| 5217 | 39 if (nargin == 1 || nargin == 2) |
| 40 if (! isvector (p)) | |
| 5216 | 41 error ("polyderiv: argument must be a vector"); |
| 42 endif | |
| 5217 | 43 if (nargin == 2) |
| 44 if (! isvector (a)) | |
| 10549 | 45 error ("polyderiv: argument must be a vector"); |
| 5217 | 46 endif |
| 47 if (nargout == 1) | |
| 10549 | 48 ## derivative of p*a returns a single polynomial |
| 49 q = polyderiv (conv (p, a)); | |
| 5217 | 50 else |
| 10549 | 51 ## derivative of p/a returns numerator and denominator |
| 52 r = conv (a, a); | |
| 53 if (numel (p) == 1) | |
| 54 q = -p * polyderiv (a); | |
| 55 elseif (numel (a) == 1) | |
| 56 q = a * polyderiv (p); | |
| 57 else | |
| 58 q = conv (polyderiv (p), a) - conv (p, polyderiv (a)); | |
| 59 q = polyreduce (q); | |
| 60 endif | |
| 5217 | 61 |
| 10549 | 62 ## remove common factors from numerator and denominator |
| 63 x = polygcd (q, r); | |
| 64 if (length(x) != 1) | |
| 65 q = deconv (q, x); | |
| 66 r = deconv (r, x); | |
| 67 endif | |
| 5217 | 68 |
| 10549 | 69 ## move all the gain into the numerator |
| 70 q = q/r(1); | |
| 71 r = r/r(1); | |
| 5217 | 72 endif |
| 5216 | 73 else |
| 5217 | 74 lp = numel (p); |
| 75 if (lp == 1) | |
| 10549 | 76 q = 0; |
| 77 return; | |
| 5217 | 78 elseif (lp == 0) |
| 10549 | 79 q = []; |
| 80 return; | |
| 5216 | 81 endif |
| 561 | 82 |
| 5217 | 83 ## Force P to be a row vector. |
| 84 p = p(:).'; | |
| 5135 | 85 |
| 5217 | 86 q = p(1:(lp-1)) .* [(lp-1):-1:1]; |
| 5216 | 87 endif |
| 88 else | |
| 6046 | 89 print_usage (); |
| 5216 | 90 endif |
| 561 | 91 |
| 7411 | 92 endfunction |
| 5217 | 93 |
| 7411 | 94 %!assert(all (all (polyderiv ([1, 2, 3]) == [2, 2]))); |
| 95 | |
| 96 %!assert(polyderiv (13) == 0); | |
| 97 | |
| 98 %!error polyderiv ([]); | |
| 99 | |
| 100 %!error polyderiv ([1, 2; 3, 4]); | |
| 101 |