/* * copyright (c) 2016 Ganesh Ajjanagadde <gajjanag@gmail.com> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * internal math functions header */ #ifndef AVUTIL_FFMATH_H#define AVUTIL_FFMATH_H #include "attributes.h"#include "libm.h" /** * Compute 10^x for floating point values. Note: this function is by no means * "correctly rounded", and is meant as a fast, reasonably accurate approximation. * For instance, maximum relative error for the double precision variant is * ~ 1e-13 for very small and very large values. * This is ~2x faster than GNU libm's approach, which is still off by 2ulp on * some inputs. * @param x exponent * @return 10^x */static av_always_inline double ff_exp10(double x){    return exp2(M_LOG2_10 * x);} static av_always_inline float ff_exp10f(float x){    return exp2f(M_LOG2_10 * x);} /** * Compute x^y for floating point x, y. Note: this function is faster than the * libm variant due to mainly 2 reasons: * 1. It does not handle any edge cases. In particular, this is only guaranteed * to work correctly for x > 0. * 2. It is not as accurate as a standard nearly "correctly rounded" libm variant. * @param x base * @param y exponent * @return x^y */static av_always_inline float ff_fast_powf(float x, float y){    return expf(logf(x) * y);} #endif /* AVUTIL_FFMATH_H */