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1 ## Copyright (C) 2000 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 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, 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} {@var{b} =} unwrap (@var{a}, @var{tol}, @var{dim}) |
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22 ## |
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23 ## Unwrap radian phases by adding multiples of 2*pi as appropriate to |
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24 ## remove jumps greater than @var{tol}. @var{tol} defaults to pi. |
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25 ## |
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26 ## Unwrap will unwrap along the first non-singleton dimension of |
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27 ## @var{a}, unless the optional argument @var{dim} is given, in |
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28 ## which case the data will be unwrapped along this dimension |
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29 ## @end deftypefn |
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30 |
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31 ## Author: Bill Lash <lash@tellabs.com> |
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32 |
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33 function retval = unwrap (a, tol, dim) |
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34 |
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35 if (nargin < 1 || nargin > 3) |
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36 usage ("unwrap (a [, tol [, dim]])") |
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37 endif |
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38 |
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39 nd = ndims (a); |
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40 sz = size (a); |
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41 |
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42 if (nargin == 3) |
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43 if (! (isscalar (dim) && dim == round (dim)) && dim > 0 && |
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44 dim < (nd + 1)) |
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45 error ("unwrap: dim must be an integer and valid dimension"); |
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46 endif |
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47 else |
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48 ## Find the first non-singleton dimension |
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49 dim = 1; |
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50 while (dim < nd + 1 && sz (dim) == 1) |
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51 dim = dim + 1; |
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52 endwhile |
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53 if (dim > nd) |
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54 dim = 1; |
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55 endif |
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56 endif |
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57 |
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58 if (nargin < 2 || isempty (tol)) |
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59 tol = pi; |
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60 endif |
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61 |
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62 ## Don't let anyone use a negative value for TOL. |
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63 tol = abs (tol); |
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64 |
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65 rng = 2*pi; |
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66 m = sz (dim); |
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67 |
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68 ## Handle case where we are trying to unwrap a scalar, or only have |
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69 ## one sample in the specified dimension. |
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70 if (m == 1) |
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71 retval = a; |
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72 return; |
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73 endif |
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74 |
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75 ## Take first order difference to see so that wraps will show up |
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76 ## as large values, and the sign will show direction. |
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77 idx = cell (); |
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78 for i = 1:nd |
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79 idx {i} = 1:sz(i); |
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80 endfor |
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81 idx {dim} = [1,1:m-1]; |
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82 d = a (idx {:}) - a; |
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83 |
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84 ## Find only the peaks, and multiply them by the range so that there |
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85 ## are kronecker deltas at each wrap point multiplied by the range |
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86 ## value. |
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87 p = rng * (((d > tol) > 0) - ((d < -tol) > 0)); |
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88 |
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89 ## Now need to "integrate" this so that the deltas become steps. |
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90 r = cumsum (p, dim); |
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91 |
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92 ## Now add the "steps" to the original data and put output in the |
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93 ## same shape as originally. |
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94 retval = a + r; |
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95 |
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96 endfunction |
