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1 ## Copyright (C) 2000, 2002, 2004, 2005, 2006, 2007, 2008 Bill Lash |
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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 3 of the License, or (at |
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8 ## your option) 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, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {@var{b} =} unwrap (@var{a}, @var{tol}, @var{dim}) |
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21 ## |
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22 ## Unwrap radian phases by adding multiples of 2*pi as appropriate to |
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23 ## remove jumps greater than @var{tol}. @var{tol} defaults to pi. |
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24 ## |
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25 ## Unwrap will unwrap along the first non-singleton dimension of |
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26 ## @var{a}, unless the optional argument @var{dim} is given, in |
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27 ## which case the data will be unwrapped along this dimension |
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28 ## @end deftypefn |
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29 |
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30 ## Author: Bill Lash <lash@tellabs.com> |
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31 |
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32 function retval = unwrap (a, tol, dim) |
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33 |
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34 if (nargin < 1 || nargin > 3) |
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35 print_usage (); |
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36 endif |
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37 |
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38 nd = ndims (a); |
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39 sz = size (a); |
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40 |
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41 if (nargin == 3) |
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42 if (! (isscalar (dim) && dim == round (dim)) && dim > 0 && |
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43 dim < (nd + 1)) |
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44 error ("unwrap: dim must be an integer and valid dimension"); |
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45 endif |
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46 else |
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47 ## Find the first non-singleton dimension |
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48 dim = 1; |
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49 while (dim < nd + 1 && sz(dim) == 1) |
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50 dim = dim + 1; |
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51 endwhile |
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52 if (dim > nd) |
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53 dim = 1; |
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54 endif |
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55 endif |
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56 |
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57 if (nargin < 2 || isempty (tol)) |
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58 tol = pi; |
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59 endif |
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60 |
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61 ## Don't let anyone use a negative value for TOL. |
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62 tol = abs (tol); |
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63 |
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64 rng = 2*pi; |
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65 m = sz(dim); |
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66 |
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67 ## Handle case where we are trying to unwrap a scalar, or only have |
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68 ## one sample in the specified dimension. |
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69 if (m == 1) |
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70 retval = a; |
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71 return; |
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72 endif |
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73 |
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74 ## Take first order difference to see so that wraps will show up |
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75 ## as large values, and the sign will show direction. |
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76 idx = cell (); |
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77 for i = 1:nd |
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78 idx{i} = 1:sz(i); |
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79 endfor |
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80 idx{dim} = [1,1:m-1]; |
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81 d = a(idx{:}) - a; |
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82 |
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83 ## Find only the peaks, and multiply them by the range so that there |
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84 ## are kronecker deltas at each wrap point multiplied by the range |
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85 ## value. |
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86 p = rng * (((d > tol) > 0) - ((d < -tol) > 0)); |
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87 |
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88 ## Now need to "integrate" this so that the deltas become steps. |
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89 r = cumsum (p, dim); |
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90 |
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91 ## Now add the "steps" to the original data and put output in the |
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92 ## same shape as originally. |
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93 retval = a + r; |
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94 |
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95 endfunction |
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96 |
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97 %!function t = xassert(a,b,tol) |
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98 %! if (nargin == 1) |
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99 %! t = all(a(:)); |
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100 %! else |
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101 %! if (nargin == 2) |
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102 %! tol = 0; |
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103 %! endif |
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104 %! if (any (size(a) != size(b))) |
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105 %! t = 0; |
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106 %! elseif (any (abs(a(:) - b(:)) > tol)) |
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107 %! t = 0; |
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108 %! else |
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109 %! t = 1; |
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110 %! endif |
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111 %! endif |
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112 %! |
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113 %!test |
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114 %! |
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115 %! i = 0; |
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116 %! t = []; |
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117 %! |
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118 %! r = [0:100]; # original vector |
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119 %! w = r - 2*pi*floor((r+pi)/(2*pi)); # wrapped into [-pi,pi] |
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120 %! tol = 1e3*eps; # maximum expected deviation |
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121 %! |
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122 %! t(++i) = xassert(r, unwrap(w), tol); #unwrap single row |
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123 %! t(++i) = xassert(r', unwrap(w'), tol); #unwrap single column |
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124 %! t(++i) = xassert([r',r'], unwrap([w',w']), tol); #unwrap 2 columns |
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125 %! t(++i) = xassert([r;r], unwrap([w;w],[],2), tol); #verify that dim works |
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126 %! t(++i) = xassert(r+10, unwrap(10+w), tol); #verify that r(1)>pi works |
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127 %! |
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128 %! t(++i) = xassert(w', unwrap(w',[],2)); #unwrap col by rows should not change it |
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129 %! t(++i) = xassert(w, unwrap(w,[],1)); #unwrap row by cols should not change it |
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130 %! t(++i) = xassert([w;w], unwrap([w;w])); #unwrap 2 rows by cols should not change them |
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131 %! |
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132 %! ## verify that setting tolerance too low will cause bad results. |
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133 %! t(++i) = xassert(any(abs(r - unwrap(w,0.8)) > 100)); |
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134 %! |
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135 %! assert(all(t)); |
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136 |
