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1 ## Copyright (C) 1995, 1998 Auburn University. All rights reserved. |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by the |
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7 ## Free Software Foundation; either version 2, or (at your option) any |
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8 ## later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but WITHOUT |
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11 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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13 ## for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301 USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} polyout (@var{c}, @var{x}) |
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22 ## Write formatted polynomial |
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23 ## @iftex |
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24 ## @tex |
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25 ## $$ c(x) = c_1 x^n + \ldots + c_n x + c_{n+1} $$ |
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26 ## @end tex |
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27 ## @end iftex |
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28 ## @ifinfo |
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29 ## @example |
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30 ## c(x) = c(1) * x^n + ... + c(n) x + c(n+1) |
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31 ## @end example |
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32 ## @end ifinfo |
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33 ## and return it as a string or write it to the screen (if |
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34 ## @var{nargout} is zero). |
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35 ## @var{x} defaults to the string @code{"s"}. |
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36 ## @end deftypefn |
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37 ## |
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38 ## @seealso{polyval, polyvalm, poly, roots, conv, deconv, residue, |
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39 ## filter, polyderiv, and polyinteg} |
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40 |
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41 ## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu> |
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42 ## Created: May 1995 |
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43 ## Nov 1998: Correctly handles complex coefficients |
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44 |
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45 function y = polyout (c, x) |
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46 |
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47 if (nargin < 1) || (nargin > 2) || (nargout < 0) || (nargout > 1) |
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48 usage("polyout (c, x)"); |
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49 endif |
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50 |
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51 if (! isvector (c)) |
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52 error("polyout: first argument must be a vector"); |
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53 endif |
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54 |
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55 if (nargin == 1) |
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56 x = "s"; |
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57 elseif (! isstr(x)) |
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58 error("polyout: second argument must be a string"); |
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59 endif |
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60 |
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61 n = length(c); |
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62 if(n > 0) |
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63 n1 = n+1; |
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64 |
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65 |
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66 tmp = coeff (c(1)); |
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67 for ii = 2:n |
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68 if (real (c(ii)) < 0) |
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69 ns = " - "; |
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70 c(ii) = -c(ii); |
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71 else |
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72 ns = " + "; |
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73 endif |
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74 |
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75 tmp = sprintf ("%s*%s^%d%s%s", tmp, x, n1-ii, ns, coeff (c(ii))); |
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76 |
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77 endfor |
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78 else |
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79 tmp = " "; |
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80 endif |
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81 |
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82 if(nargout == 0) |
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83 disp(tmp) |
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84 else |
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85 y = tmp; |
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86 endif |
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87 |
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88 endfunction |
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89 |
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90 function str = coeff(c) |
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91 if (imag (c)) |
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92 if (real (c)) |
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93 str = sprintf ("(%s)", com2str(c)); |
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94 else |
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95 str = com2str(c); |
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96 endif |
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97 else |
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98 str = num2str(c); |
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99 endif |
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100 |
