Mathematics and Statistics
[Miscelaneous]

Data Structures
struct	pj_math_stat
Defines
#define	PJ_PI   3.14159265358979323846
#define	PJ_1_PI   0.318309886183790671538
#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))
Functions
unsigned	pj_isqrt (unsigned i)
void	pj_math_stat_init (pj_math_stat *stat)
void	pj_math_stat_update (pj_math_stat *stat, int val)
unsigned	pj_math_stat_get_stddev (const pj_math_stat *stat)
void	pj_math_stat_set_stddev (pj_math_stat *stat, unsigned dev)

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Detailed Description

Provides common mathematics constants and operations, and also standard statistics calculation (min, max, mean, standard deviation). Statistics calculation is done in realtime (statistics state is updated on time each new sample comes).

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Define Documentation

#define PJ_ABS

(

x

)

((x) > 0 ? (x) : -(x))

Mathematical macro

#define PJ_PI   3.14159265358979323846

Mathematical constants

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Function Documentation

unsigned pj_isqrt

(

unsigned

i

)

Calculate integer square root of an integer.

Parameters:

i

Integer to be calculated.

Returns:

Square root result.

Referenced by pj_math_stat_get_stddev().

unsigned pj_math_stat_get_stddev

(

const pj_math_stat *

stat

)

Get the standard deviation of specified statistics state.

Parameters:

stat

Statistic state.

Returns:

The standard deviation.

References pj_isqrt().

void pj_math_stat_init

(

pj_math_stat *

stat

)

Initialize statistics state.

Parameters:

stat

Statistic state.

References pj_bzero().

void pj_math_stat_set_stddev	(	pj_math_stat *	stat,
		unsigned	dev
	)

Set the standard deviation of statistics state. This is useful when the statistic state is operated in 'read-only' mode as a storage of statistical data.

Parameters:

	stat	Statistic state.
	dev	The standard deviation.

void pj_math_stat_update	(	pj_math_stat *	stat,
		int	val
	)

Update statistics state as a new sample comes.

Parameters:

	stat	Statistic state.
	val	The new sample data.

References int().