BLOG | DOCUMENTATION | TRAC |  Home --> Documentations --> PJLIB Reference math.h Go to the documentation of this file. /* $Id: math.h 3553 2011-05-05 06:14:19Z nanang $ */ /* * 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__ #include <pj/string.h> #include <pj/compat/high_precision.h> PJ_BEGIN_DECL #define PJ_PI 3.14159265358979323846 /* pi */ #define PJ_1_PI 0.318309886183790671538 /* 1/pi */ #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)) 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; 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; } PJ_INLINE(void) pj_math_stat_init(pj_math_stat *stat) { pj_bzero(stat, sizeof(pj_math_stat)); } 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 } 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))); } 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__ */   PJLIB Open Source, high performance, small footprint, and very very portable framework Copyright (C) 2006-2009 Teluu Inc.