Mercurial > hg > octave-lyh
annotate scripts/signal/detrend.m @ 11469:c776f063fefe
Overhaul m-script files to use common variable name between code and documentation.
| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Sun, 09 Jan 2011 12:41:21 -0800 |
| parents | dd539a976451 |
| children | fd0a3ac60b0e |
| rev | line source |
|---|---|
| 7017 | 1 ## Copyright (C) 1995, 1996, 1999, 2000, 2002, 2005, 2006, 2007 |
| 2 ## Kurt Hornik | |
| 3426 | 3 ## |
| 3922 | 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. | |
| 3426 | 10 ## |
| 3922 | 11 ## Octave is distributed in the hope that it will be useful, but |
| 2539 | 12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 3426 | 14 ## General Public License for more details. |
| 15 ## | |
| 2539 | 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/>. | |
| 2539 | 19 |
| 3381 | 20 ## -*- texinfo -*- |
| 3367 | 21 ## @deftypefn {Function File} {} detrend (@var{x}, @var{p}) |
| 22 ## If @var{x} is a vector, @code{detrend (@var{x}, @var{p})} removes the | |
| 23 ## best fit of a polynomial of order @var{p} from the data @var{x}. | |
| 3426 | 24 ## |
| 3367 | 25 ## If @var{x} is a matrix, @code{detrend (@var{x}, @var{p})} does the same |
| 26 ## for each column in @var{x}. | |
| 3426 | 27 ## |
| 3367 | 28 ## The second argument is optional. If it is not specified, a value of 1 |
| 29 ## is assumed. This corresponds to removing a linear trend. | |
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11409
dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
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30 ## |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
31 ## The order of the polynomial can also be given as a string, in which case |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
32 ## @var{p} must be either @t{"constant"} (corresponds to @code{@var{p}=0}) or |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
33 ## @t{"linear"} (corresponds to @code{@var{p}=1}). |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
34 ## @seealso{polyfit} |
| 3367 | 35 ## @end deftypefn |
| 2539 | 36 |
| 5428 | 37 ## Author: KH <Kurt.Hornik@wu-wien.ac.at> |
| 2539 | 38 ## Created: 11 October 1994 |
| 39 ## Adapted-By: jwe | |
| 3426 | 40 |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
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41 function y = detrend (x, p = 1) |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
42 ## Check input |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
43 if (nargin > 0 && isreal (x) && ndims (x) <= 2) |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
44 ## Check p |
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dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
45 if (ischar (p) && strcmpi (p, "constant")) |
|
dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
46 p = 0; |
|
dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
47 elseif (ischar (p) && strcmpi (p, "linear")) |
|
dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
48 p = 1; |
|
dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
49 elseif (!isscalar (p) || p < 0 || p != round (p)) |
|
dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
50 error ("detrend: second input argument must be 'constant', 'linear' or a positive integer"); |
| 2539 | 51 endif |
| 52 else | |
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11409
dd539a976451
signal/detrend.m: Also accept polynomial order as a string for compatibility
Soren Hauberg <hauberg@gmail.com>
parents:
7279
diff
changeset
|
53 error ("detrend: first input argument must be a real vector or matrix"); |
| 2539 | 54 endif |
| 3426 | 55 |
| 2539 | 56 [m, n] = size (x); |
| 57 if (m == 1) | |
| 58 x = x'; | |
| 59 endif | |
| 3426 | 60 |
| 2539 | 61 r = rows (x); |
| 62 b = ((1 : r)' * ones (1, p + 1)) .^ (ones (r, 1) * (0 : p)); | |
| 63 y = x - b * (b \ x); | |
| 3426 | 64 |
| 2539 | 65 if (m == 1) |
| 66 y = y'; | |
| 67 endif | |
| 3426 | 68 |
| 2539 | 69 endfunction |
| 7279 | 70 |
| 71 %!test | |
| 72 %! N=32; | |
| 73 %! x = (0:1:N-1)/N + 2; | |
| 74 %! y = detrend(x); | |
| 75 %! assert(all (all (abs (y) < 20*eps))); | |
| 76 | |
| 77 %!test | |
| 78 %! N=32; | |
| 79 %! t = (0:1:N-1)/N; | |
| 80 %! x = t .* t + 2; | |
| 81 %! y = detrend(x,2); | |
| 82 %! assert(all (all (abs (y) < 30*eps))); | |
| 83 | |
| 84 %!test | |
| 85 %! N=32; | |
| 86 %! t = (0:1:N-1)/N; | |
| 87 %! x = [t;4*t-3]'; | |
| 88 %! y = detrend(x); | |
| 89 %! assert(all (all (abs (y) < 20*eps))); | |
| 90 |