2 Copyright (C) 2003-2009 Paul Brossier <piem@aubio.org>
4 This file is part of aubio.
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.
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.
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/>.
22 * various math functions
29 #include "musicutils.h"
35 /** compute the mean of a vector
37 \param s vector to compute mean from
42 smpl_t fvec_mean (fvec_t * s);
44 /** find the max of a vector
46 \param s vector to get the max from
48 \return the value of the minimum of v
51 smpl_t fvec_max (fvec_t * s);
53 /** find the min of a vector
55 \param s vector to get the min from
57 \return the value of the maximum of v
60 smpl_t fvec_min (fvec_t * s);
62 /** find the index of the min of a vector
64 \param s vector to get the index from
66 \return the index of the minimum element of v
69 uint_t fvec_min_elem (fvec_t * s);
71 /** find the index of the max of a vector
73 \param s vector to get the index from
75 \return the index of the maximum element of v
78 uint_t fvec_max_elem (fvec_t * s);
80 /** swap the left and right halves of a vector
82 This function swaps the left part of the signal with the right part of the
85 \f$ a[0], a[1], ..., a[\frac{N}{2}], a[\frac{N}{2}+1], ..., a[N-1], a[N] \f$
89 \f$ a[\frac{N}{2}+1], ..., a[N-1], a[N], a[0], a[1], ..., a[\frac{N}{2}] \f$
91 This operation, known as 'fftshift' in the Matlab Signal Processing Toolbox,
92 can be used before computing the FFT to simplify the phase relationship of the
93 resulting spectrum. See Amalia de Götzen's paper referred to above.
96 void fvec_shift (fvec_t * v);
98 /** compute the sum of all elements of a vector
100 \param v vector to compute the sum of
105 smpl_t fvec_sum (fvec_t * v);
107 /** compute the energy of a vector
109 This function compute the sum of the squared elements of a vector.
111 \param v vector to get the energy from
113 \return the energy of v
116 smpl_t fvec_local_energy (fvec_t * v);
118 /** compute the High Frequency Content of a vector
120 The High Frequency Content is defined as \f$ \sum_0^{N-1} (k+1) v[k] \f$.
122 \param v vector to get the energy from
127 smpl_t fvec_local_hfc (fvec_t * v);
129 /** computes the p-norm of a vector
131 Computes the p-norm of a vector for \f$ p = \alpha \f$
133 \f$ L^p = ||x||_p = (|x_1|^p + |x_2|^p + ... + |x_n|^p ) ^ \frac{1}{p} \f$
135 If p = 1, the result is the Manhattan distance.
137 If p = 2, the result is the Euclidean distance.
139 As p tends towards large values, \f$ L^p \f$ tends towards the maximum of the
144 - <a href="http://en.wikipedia.org/wiki/Lp_space">\f$L^p\f$ space</a> on
147 \param v vector to compute norm from
148 \param p order of the computed norm
150 \return the p-norm of v
153 smpl_t fvec_alpha_norm (fvec_t * v, smpl_t p);
155 /** alpha normalisation
157 This function divides all elements of a vector by the p-norm as computed by
160 \param v vector to compute norm from
161 \param p order of the computed norm
164 void fvec_alpha_normalise (fvec_t * v, smpl_t p);
166 /** add a constant to each elements of a vector
168 \param v vector to add constant to
169 \param c constant to add to v
172 void fvec_add (fvec_t * v, smpl_t c);
174 /** remove the minimum value of the vector to each elements
176 \param v vector to remove minimum from
179 void fvec_min_removal (fvec_t * v);
181 /** compute moving median theshold of a vector
183 This function computes the moving median threshold value of at the given
184 position of a vector, taking the median amongs post elements before and up to
185 pre elements after pos.
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
193 \return moving median threshold value
196 smpl_t fvec_moving_thres (fvec_t * v, fvec_t * tmp, uint_t post, uint_t pre,
199 /** apply adaptive threshold to a vector
201 For each points at position p of an input vector, this function remove the
202 moving median threshold computed at p.
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
210 void fvec_adapt_thres (fvec_t * v, fvec_t * tmp, uint_t post, uint_t pre);
212 /** returns the median of a vector
214 The QuickSelect routine is based on the algorithm described in "Numerical
215 recipes in C", Second Edition, Cambridge University Press, 1992, Section 8.5,
218 This implementation of the QuickSelect routine is based on Nicolas
219 Devillard's implementation, available at http://ndevilla.free.fr/median/median/
220 and in the Public Domain.
222 \param v vector to get median from
224 \return the median of v
227 smpl_t fvec_median (fvec_t * v);
229 /** finds exact peak index by quadratic interpolation*/
230 smpl_t fvec_quadint (fvec_t * x, uint_t pos);
232 /** Quadratic interpolation using Lagrange polynomial.
234 Inspired from ``Comparison of interpolation algorithms in real-time sound
235 processing'', Vladimir Arnost,
237 \param s0,s1,s2 are 3 consecutive samples of a curve
238 \param pf is the floating point index [0;2]
240 \return s0 + (pf/2.)*((pf-3.)*s0-2.*(pf-2.)*s1+(pf-1.)*s2);
243 smpl_t aubio_quadfrac (smpl_t s0, smpl_t s1, smpl_t s2, smpl_t pf);
245 /** return 1 if v[p] is a peak and positive, 0 otherwise
247 This function returns 1 if a peak is found at index p in the vector v. The
248 peak is defined as follows:
254 \param v input vector
255 \param p position of supposed for peak
257 \return 1 if a peak is found, 0 otherwise
260 uint_t fvec_peakpick (fvec_t * v, uint_t p);
262 /** return 1 if a is a power of 2, 0 otherwise */
263 uint_t aubio_is_power_of_two(uint_t a);
265 /** return the next power of power of 2 greater than a */
266 uint_t aubio_next_power_of_two(uint_t a);
268 /** compute normalised autocorrelation function
270 \param input vector to compute autocorrelation from
271 \param output vector to store autocorrelation function to
274 void aubio_autocorr (fvec_t * input, fvec_t * output);