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- /*
- * 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 */
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