ffmath.h File Reference

#include "attributes.h"
#include "libm.h"

Go to the source code of this file.

Functions
static av_always_inline double	ff_exp10 (double x)
	Compute 10^x for floating point values. More...
static av_always_inline float	ff_exp10f (float x)
static av_always_inline float	ff_fast_powf (float x, float y)
	Compute x^y for floating point x, y. More...

Detailed Description

internal math functions header

Definition in file ffmath.h.

Function Documentation

ff_exp10()

static av_always_inline double ff_exp10 ( double  x )

static

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.

Parameters

x

exponent

Returns

10^x

Definition at line 42 of file ffmath.h.

Referenced by ap_init(), av_strtod(), butterworth_bp_filter(), chebyshev1_bp_filter(), chebyshev2_bp_filter(), cng_decode_frame(), config_filter(), config_input(), config_output(), convert_dir2zdf(), convert_width2qfactor(), decode_subframe(), encode_block(), encode_init(), ff_acelp_decode_gain_code(), ff_amr_set_fixed_gain(), ff_opus_parse_extradata(), filter_frame(), iac_generate_tabs(), init_exp(), libopus_decode_init(), on2avc_decode_init(), psy_3gpp_init(), read16_fft_bin(), read8_fft_bin(), and wma_decode_block().

ff_exp10f()

static av_always_inline float ff_exp10f ( float  x )

static

Definition at line 47 of file ffmath.h.

ff_fast_powf()

static av_always_inline float ff_fast_powf ( float  x, float  y  )

static

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.

   Parameters

   x	base
   y	exponent

   Returns

   x^y

Definition at line 62 of file ffmath.h.

Referenced by find_form_factor().