NW_Readings

Fixed-capacity store for one measurement’s readings, with statistics. More…

#include <NW_Readings.h>

Public Functions

	Name
void	reset()
void	append(T v)
uint16_t	count() const
T	last() const The newest reading (meaningful only if count() > 0).
const T *	data() const The readings, in storage order (not chronological after a wrap; statistics do not care).
float	mean() const
float	std() const Sample standard deviation (n-1); 0 for a single reading.
float	sterr() const Standard error of the mean, std / sqrt(n); 0 for a single reading.
float	median() const Median: copies the readings once and insertion-sorts (n <= CAPACITY).
constexpr uint16_t	capacity()

Public Attributes

	Name
constexpr float	NW_READINGS_EMPTY returned by the statistics when count() == 0: the file sentinel

Detailed Description

template <typename T ,
uint16_t CAPACITY>
class NW_Readings;

Fixed-capacity store for one measurement’s readings, with statistics.

Template Parameters:

• T element type (int16_t, uint16_t, uint32_t, float)
• CAPACITY number of readings kept

One storage path (LIBRARY-DESIGN, decided 2026-09-22): every acquisition appends here; the scalar getter of a library returns last(); the statistics are computed from the array on demand, so a batch logged through logReading() has its statistics without a second acquisition. Appending past CAPACITY overwrites the oldest reading (the newest CAPACITY readings are kept). No heap. mean/std/sterr are two-pass in float, exact enough for CAPACITY up to a few hundred; median copies the array once onto the stack (CAPACITY * sizeof(T) bytes), so keep CAPACITY modest on small AVRs.

Public Functions Documentation

function reset

inline void reset()

function append

inline void append(
    T v
)

function count

inline uint16_t count() const

function last

inline T last() const

The newest reading (meaningful only if count() > 0).

function data

inline const T * data() const

The readings, in storage order (not chronological after a wrap; statistics do not care).

function mean

inline float mean() const

function std

inline float std() const

Sample standard deviation (n-1); 0 for a single reading.

function sterr

inline float sterr() const

Standard error of the mean, std / sqrt(n); 0 for a single reading.

function median

inline float median() const

Median: copies the readings once and insertion-sorts (n <= CAPACITY).

function capacity

static inline constexpr uint16_t capacity()

Public Attributes Documentation

variable NW_READINGS_EMPTY

static constexpr float NW_READINGS_EMPTY = NW_ERROR;

returned by the statistics when count() == 0: the file sentinel

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Updated on 2026-09-23 at 22:42:22 +0000