| /* |
| * 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 */ |
