| /* $Id$ */ |
| /* |
| * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com) |
| * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| |
| #ifndef __PJ_MATH_H__ |
| #define __PJ_MATH_H__ |
| |
| /** |
| * @file math.h |
| * @brief Mathematics and Statistics. |
| */ |
| |
| #include <pj/string.h> |
| #include <pj/compat/high_precision.h> |
| |
| PJ_BEGIN_DECL |
| |
| /** |
| * @defgroup pj_math Mathematics and Statistics |
| * @ingroup PJ_MISC |
| * @{ |
| * |
| * Provides common mathematics constants and operations, and also standard |
| * statistics calculation (min, max, mean, standard deviation). Statistics |
| * calculation is done in realtime (statistics state is updated on time each |
| * new sample comes). |
| */ |
| |
| /** |
| * Mathematical constants |
| */ |
| #define PJ_PI 3.14159265358979323846 /* pi */ |
| #define PJ_1_PI 0.318309886183790671538 /* 1/pi */ |
| |
| /** |
| * Mathematical macro |
| */ |
| #define PJ_ABS(x) ((x) > 0 ? (x) : -(x)) |
| #define PJ_MAX(x, y) ((x) > (y)? (x) : (y)) |
| #define PJ_MIN(x, y) ((x) < (y)? (x) : (y)) |
| |
| /** |
| * This structure describes statistics state. |
| */ |
| typedef struct pj_math_stat |
| { |
| int n; /* number of samples */ |
| int max; /* maximum value */ |
| int min; /* minimum value */ |
| int last; /* last value */ |
| int mean; /* mean */ |
| |
| /* Private members */ |
| #if PJ_HAS_FLOATING_POINT |
| float fmean_; /* mean(floating point) */ |
| #else |
| int mean_res_; /* mean residu */ |
| #endif |
| pj_highprec_t m2_; /* variance * n */ |
| } pj_math_stat; |
| |
| /** |
| * Calculate integer square root of an integer. |
| * |
| * @param i Integer to be calculated. |
| * |
| * @return Square root result. |
| */ |
| PJ_INLINE(unsigned) pj_isqrt(unsigned i) |
| { |
| unsigned res = 1, prev; |
| |
| /* Rough guess, calculate half bit of input */ |
| prev = i >> 2; |
| while (prev) { |
| prev >>= 2; |
| res <<= 1; |
| } |
| |
| /* Babilonian method */ |
| do { |
| prev = res; |
| res = (prev + i/prev) >> 1; |
| } while ((prev+res)>>1 != res); |
| |
| return res; |
| } |
| |
| /** |
| * Initialize statistics state. |
| * |
| * @param stat Statistic state. |
| */ |
| PJ_INLINE(void) pj_math_stat_init(pj_math_stat *stat) |
| { |
| pj_bzero(stat, sizeof(pj_math_stat)); |
| } |
| |
| /** |
| * Update statistics state as a new sample comes. |
| * |
| * @param stat Statistic state. |
| * @param val The new sample data. |
| */ |
| PJ_INLINE(void) pj_math_stat_update(pj_math_stat *stat, int val) |
| { |
| #if PJ_HAS_FLOATING_POINT |
| float delta; |
| #else |
| int delta; |
| #endif |
| |
| stat->last = val; |
| |
| if (stat->n++) { |
| if (stat->min > val) |
| stat->min = val; |
| if (stat->max < val) |
| stat->max = val; |
| } else { |
| stat->min = stat->max = val; |
| } |
| |
| #if PJ_HAS_FLOATING_POINT |
| delta = val - stat->fmean_; |
| stat->fmean_ += delta/stat->n; |
| |
| /* Return mean value with 'rounding' */ |
| stat->mean = (int) (stat->fmean_ + 0.5); |
| |
| stat->m2_ += (int)(delta * (val-stat->fmean_)); |
| #else |
| delta = val - stat->mean; |
| stat->mean += delta/stat->n; |
| stat->mean_res_ += delta % stat->n; |
| if (stat->mean_res_ >= stat->n) { |
| ++stat->mean; |
| stat->mean_res_ -= stat->n; |
| } else if (stat->mean_res_ <= -stat->n) { |
| --stat->mean; |
| stat->mean_res_ += stat->n; |
| } |
| |
| stat->m2_ += delta * (val-stat->mean); |
| #endif |
| } |
| |
| /** |
| * Get the standard deviation of specified statistics state. |
| * |
| * @param stat Statistic state. |
| * |
| * @return The standard deviation. |
| */ |
| PJ_INLINE(unsigned) pj_math_stat_get_stddev(const pj_math_stat *stat) |
| { |
| if (stat->n == 0) return 0; |
| return (pj_isqrt((unsigned)(stat->m2_/stat->n))); |
| } |
| |
| /** |
| * Set the standard deviation of statistics state. This is useful when |
| * the statistic state is operated in 'read-only' mode as a storage of |
| * statistical data. |
| * |
| * @param stat Statistic state. |
| * |
| * @param dev The standard deviation. |
| */ |
| PJ_INLINE(void) pj_math_stat_set_stddev(pj_math_stat *stat, unsigned dev) |
| { |
| if (stat->n == 0) |
| stat->n = 1; |
| stat->m2_ = dev*dev*stat->n; |
| } |
| |
| /** @} */ |
| |
| PJ_END_DECL |
| |
| #endif /* __PJ_MATH_H__ */ |