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1 ## Copyright (C) 1996, 1997 John W. Eaton |
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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 |
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7 ## the Free Software Foundation; either version 2, or (at your option) |
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8 ## any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License 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, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} stairs (@var{x}, @var{y}) |
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22 ## Given two vectors of x-y data, bar produces a `stairstep' plot. |
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23 ## |
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24 ## If only one argument is given, it is taken as a vector of y-values |
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25 ## and the x coordinates are taken to be the indices of the elements. |
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26 ## |
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27 ## If two output arguments are specified, the data are generated but |
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28 ## not plotted. For example, |
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29 ## |
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30 ## @example |
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31 ## stairs (x, y); |
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32 ## @end example |
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33 ## |
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34 ## @noindent |
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35 ## and |
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36 ## |
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37 ## @example |
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38 ## [xs, ys] = stairs (x, y); |
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39 ## plot (xs, ys); |
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40 ## @end example |
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41 ## |
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42 ## @noindent |
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43 ## are equivalent. |
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44 ## @end deftypefn |
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45 ## |
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46 ## @seealso{plot, semilogx, semilogy, loglog, polar, mesh, contour, |
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47 ## bar, replot, xlabel, ylabel, and title} |
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48 |
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49 ## Author: jwe |
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50 |
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51 function [xs, ys] = stairs (x, y) |
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52 |
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53 |
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54 if (nargin == 1) |
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55 if (isvector (x)) |
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56 len = 2 * length (x); |
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57 tmp_xs = tmp_ys = zeros (len, 1); |
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58 k = 0; |
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59 for i = 1:2:len |
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60 tmp_xs(i) = k++; |
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61 tmp_ys(i) = x(k); |
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62 tmp_ys(i+1) = x(k); |
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63 tmp_xs(i+1) = k; |
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64 endfor |
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65 else |
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66 error ("stairs: argument must be a vector"); |
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67 endif |
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68 elseif (nargin == 2) |
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69 if (isvector (x) && isvector (y)) |
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70 xlen = length (x); |
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71 ylen = length (y); |
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72 if (xlen == ylen) |
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73 len = 2 * xlen; |
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74 tmp_xs = tmp_ys = zeros (len, 1); |
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75 k = 1; |
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76 len_m2 = len - 2; |
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77 for i = 1:2:len_m2 |
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78 tmp_xs(i) = x(k); |
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79 tmp_ys(i) = y(k); |
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80 tmp_ys(i+1) = y(k); |
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81 k++; |
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82 tmp_xs(i+1) = x(k); |
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83 if (x(k) < x(k-1)) |
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84 error ("stairs: x vector values must be in ascending order"); |
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85 endif |
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86 endfor |
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87 tmp_xs(len-1) = x(xlen); |
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88 delta = x(xlen) - x(xlen-1); |
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89 tmp_xs(len) = x(xlen) + delta; |
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90 tmp_ys(len-1) = y(ylen); |
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91 tmp_ys(len) = y(ylen); |
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92 else |
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93 error ("stairs: arguments must be the same length"); |
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94 endif |
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95 else |
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96 error ("stairs: arguments must be vectors"); |
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97 endif |
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98 else |
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99 usage ("[xs, ys] = stairs (x, y)"); |
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100 endif |
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101 |
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102 if (nargout == 0) |
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103 plot (tmp_xs, tmp_ys); |
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104 else |
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105 xs = tmp_xs; |
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106 ys = tmp_ys; |
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107 endif |
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108 |
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109 endfunction |
