source: src/mathutils.h @ 8e5c051

feature/autosinkfeature/cnnfeature/cnn_orgfeature/constantqfeature/crepefeature/crepe_orgfeature/pitchshiftfeature/pydocstringsfeature/timestretchfix/ffmpeg5pitchshiftsamplertimestretchyinfft+
Last change on this file since 8e5c051 was 8e5c051, checked in by Paul Brossier <piem@piem.org>, 15 years ago

src/mathutils.{c,h}: switch to mono

  • Property mode set to 100644
File size: 6.7 KB
Line 
1/*
2  Copyright (C) 2003-2009 Paul Brossier <piem@aubio.org>
3
4  This file is part of aubio.
5
6  aubio is free software: you can redistribute it and/or modify
7  it under the terms of the GNU General Public License as published by
8  the Free Software Foundation, either version 3 of the License, or
9  (at your option) any later version.
10
11  aubio is distributed in the hope that it will be useful,
12  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  GNU General Public License for more details.
15
16  You should have received a copy of the GNU General Public License
17  along with aubio.  If not, see <http://www.gnu.org/licenses/>.
18
19*/
20
21/** @file
22 *  various math functions
23 */
24
25#ifndef MATHUTILS_H
26#define MATHUTILS_H
27
28#include "fvec.h"
29#include "musicutils.h"
30
31#ifdef __cplusplus
32extern "C" {
33#endif
34
35/** compute the mean of a vector
36
37  \param s vector to compute mean from
38
39  \return the mean of v
40
41*/
42smpl_t fvec_mean (fvec_t * s);
43
44/** find the max of a vector
45
46  \param s vector to get the max from
47
48  \return the value of the minimum of v
49
50*/
51smpl_t fvec_max (fvec_t * s);
52
53/** find the min of a vector
54
55  \param s vector to get the min from
56
57  \return the value of the maximum of v
58
59*/
60smpl_t fvec_min (fvec_t * s);
61
62/** find the index of the min of a vector
63
64  \param s vector to get the index from
65
66  \return the index of the minimum element of v
67
68*/
69uint_t fvec_min_elem (fvec_t * s);
70
71/** find the index of the max of a vector
72
73  \param s vector to get the index from
74
75  \return the index of the maximum element of v
76
77*/
78uint_t fvec_max_elem (fvec_t * s);
79
80/** swap the left and right halves of a vector
81 
82  This function swaps the left part of the signal with the right part of the
83signal. Therefore
84
85  \f$ a[0], a[1], ..., a[\frac{N}{2}], a[\frac{N}{2}+1], ..., a[N-1], a[N] \f$
86 
87  becomes
88 
89  \f$ a[\frac{N}{2}+1], ..., a[N-1], a[N], a[0], a[1], ..., a[\frac{N}{2}] \f$
90
91  This operation, known as 'fftshift' in the Matlab Signal Processing Toolbox,
92can be used before computing the FFT to simplify the phase relationship of the
93resulting spectrum. See Amalia de Götzen's paper referred to above.
94 
95*/
96void fvec_shift (fvec_t * v);
97
98/** compute the sum of all elements of a vector
99
100  \param v vector to compute the sum of
101
102  \return the sum of v
103
104*/
105smpl_t fvec_sum (fvec_t * v);
106
107/** compute the energy of a vector
108
109  This function compute the sum of the squared elements of a vector.
110 
111  \param v vector to get the energy from
112
113  \return the energy of v
114 
115*/
116smpl_t fvec_local_energy (fvec_t * v);
117
118/** compute the High Frequency Content of a vector
119
120  The High Frequency Content is defined as \f$ \sum_0^{N-1} (k+1) v[k] \f$.
121 
122  \param v vector to get the energy from
123
124  \return the HFC of v
125 
126*/
127smpl_t fvec_local_hfc (fvec_t * v);
128
129/** computes the p-norm of a vector
130 
131  Computes the p-norm of a vector for \f$ p = \alpha \f$
132
133  \f$ L^p = ||x||_p = (|x_1|^p + |x_2|^p + ... + |x_n|^p ) ^ \frac{1}{p} \f$
134 
135  If p = 1, the result is the Manhattan distance.
136
137  If p = 2, the result is the Euclidean distance.
138
139  As p tends towards large values, \f$ L^p \f$ tends towards the maximum of the
140input vector.
141
142  References:
143 
144    - <a href="http://en.wikipedia.org/wiki/Lp_space">\f$L^p\f$ space</a> on
145  Wikipedia
146
147  \param v vector to compute norm from
148  \param p order of the computed norm
149
150  \return the p-norm of v
151 
152*/
153smpl_t fvec_alpha_norm (fvec_t * v, smpl_t p);
154
155/**  alpha normalisation
156
157  This function divides all elements of a vector by the p-norm as computed by
158fvec_alpha_norm().
159
160  \param v vector to compute norm from
161  \param p order of the computed norm
162
163*/
164void fvec_alpha_normalise (fvec_t * v, smpl_t p);
165
166/** add a constant to each elements of a vector
167
168  \param v vector to add constant to
169  \param c constant to add to v
170
171*/
172void fvec_add (fvec_t * v, smpl_t c);
173
174/** remove the minimum value of the vector to each elements
175 
176  \param v vector to remove minimum from
177
178*/
179void fvec_min_removal (fvec_t * v);
180
181/** compute moving median theshold of a vector
182
183  This function computes the moving median threshold value of at the given
184position of a vector, taking the median amongs post elements before and up to
185pre elements after pos.
186 
187  \param v input vector
188  \param tmp temporary vector of length post+1+pre
189  \param post length of causal part to take before pos
190  \param pre length of anti-causal part to take after pos
191  \param pos index to compute threshold for
192
193  \return moving median threshold value
194
195*/
196smpl_t fvec_moving_thres (fvec_t * v, fvec_t * tmp, uint_t post, uint_t pre,
197    uint_t pos);
198
199/** apply adaptive threshold to a vector
200
201  For each points at position p of an input vector, this function remove the
202moving median threshold computed at p.
203
204  \param v input vector
205  \param tmp temporary vector of length post+1+pre
206  \param post length of causal part to take before pos
207  \param pre length of anti-causal part to take after pos
208
209*/
210void fvec_adapt_thres (fvec_t * v, fvec_t * tmp, uint_t post, uint_t pre);
211
212/** returns the median of a vector
213
214  The QuickSelect routine is based on the algorithm described in "Numerical
215recipes in C", Second Edition, Cambridge University Press, 1992, Section 8.5,
216ISBN 0-521-43108-5
217
218  This implementation of the QuickSelect routine is based on Nicolas
219Devillard's implementation, available at http://ndevilla.free.fr/median/median/
220and in the Public Domain.
221
222  \param v vector to get median from
223
224  \return the median of v
225 
226*/
227smpl_t fvec_median (fvec_t * v);
228
229/** finds exact peak index by quadratic interpolation*/
230smpl_t fvec_quadint (fvec_t * x, uint_t pos);
231
232/** Quadratic interpolation using Lagrange polynomial.
233 
234  Inspired from ``Comparison of interpolation algorithms in real-time sound
235processing'', Vladimir Arnost,
236 
237  \param s0,s1,s2 are 3 consecutive samples of a curve
238  \param pf is the floating point index [0;2]
239 
240  \return s0 + (pf/2.)*((pf-3.)*s0-2.*(pf-2.)*s1+(pf-1.)*s2);
241
242*/
243smpl_t aubio_quadfrac (smpl_t s0, smpl_t s1, smpl_t s2, smpl_t pf);
244
245/** return 1 if v[p] is a peak and positive, 0 otherwise
246
247  This function returns 1 if a peak is found at index p in the vector v. The
248peak is defined as follows:
249
250  - v[p] is positive
251  - v[p-1] < v[p]
252  - v[p] > v[p+1]
253
254  \param v input vector
255  \param p position of supposed for peak
256
257  \return 1 if a peak is found, 0 otherwise
258
259*/
260uint_t fvec_peakpick (fvec_t * v, uint_t p);
261
262/** return 1 if a is a power of 2, 0 otherwise */
263uint_t aubio_is_power_of_two(uint_t a);
264
265/** return the next power of power of 2 greater than a */
266uint_t aubio_next_power_of_two(uint_t a);
267
268/** compute normalised autocorrelation function
269
270  \param input vector to compute autocorrelation from
271  \param output vector to store autocorrelation function to
272
273*/
274void aubio_autocorr (fvec_t * input, fvec_t * output);
275
276#ifdef __cplusplus
277}
278#endif
279
280#endif
281
Note: See TracBrowser for help on using the repository browser.