gTime Class Reference

This class implements time calculations. More...

#include <gTime.hpp>

Public Member Functions
	gTime (double ai_jDays=0)
	gTime (int year, double day)
	gTime (int nYear, int nMonth, int nDay, int nHour, int nMin, double nSec)
	gTime (struct tm ai_timestruct)
	gTime (const gTime &timeSrc)
void	setTime (int year, double day)
	Set the time value of the time object to the julian day of year, day. More...
const gTime &	operator= (const gTime &timeSrc)
	overload de = operator to assign time values to he object. More...
const gTime &	operator= (time_t t)
	overload de = operator to assign time values to he object in time_t (operating system) format. More...
const gTime &	operator= (double t)
	overload the = operator to assign time values to the object in julian days. More...
double	getGmtTm () const
	Returns the time GMT value in Julian days. More...
double	getLocalTm () const
	Returns the time Local value in Julian days. More...
time_t	toTime () const
	Returns the time_t value of the gTime Object. More...
void	toCalendarDate (int *pYear, int *pMonth, double *pDom) const
double	toJCenturies () const
double	toThetaGMST () const
	Calculate Theta Angle at Greenwich Mean Time for the Julian date. More...
double	toThetaLMST (double longitude) const
	Calculate Theta Angle at Local Mean Time for the Julian date. More...
gTimeSpan	operator- (gTime time) const
gTime	operator- (gTimeSpan timeSpan) const
gTime	operator+ (gTimeSpan timeSpan) const
const gTime &	operator+= (gTimeSpan timeSpan)
const gTime &	operator-= (gTimeSpan timeSpan)
bool	operator== (gTime time) const
bool	operator!= (gTime time) const
bool	operator< (gTime time) const
bool	operator> (gTime time) const
bool	operator<= (gTime time) const
bool	operator>= (gTime time) const

Static Public Member Functions
static gTime	getCurrentTime ()
	Returns a gTime object set with the actual machine time. More...
static gTimeSpan	getTimeToUTC ()
	Returns a gTimeSpan object set with the Local Time Span set in the machine. More...
static bool	isLeapYear (int ai_year)
	Leap Year Calculation. More...

Detailed Description

This class implements time calculations.

Time is stored in julian days

• Time getting in GMT, Local and Sidereal (earth rotational angle)
• Time Math operations.

Member Function Documentation

getCurrentTime()

static gTime gTime::getCurrentTime ( )

static

Returns a gTime object set with the actual machine time.

Warning

This method works with the operating system function time. So it doesn't support seconds fractions

Returns

gTime Object assigned with real machine time.

getGmtTm()

double gTime::getGmtTm

(

)

const

Returns the time GMT value in Julian days.

Returns

: double Julian Days represented in the gTime Object

getLocalTm()

double gTime::getLocalTm

(

)

const

Returns the time Local value in Julian days.

Returns

: double Julian Days represented in the gTime Object

getTimeToUTC()

static gTimeSpan gTime::getTimeToUTC ( )

static

Returns a gTimeSpan object set with the Local Time Span set in the machine.

Returns

gTimeSpan Object assigned with the real machine GMT Diff.

isLeapYear()

static bool gTime::isLeapYear ( int  ai_year )

inlinestatic

Leap Year Calculation.

This Operation uses the standard algorithm to calculate Leap Years. Reference: http://en.wikipedia.org/wiki/Leap_year

Parameters

ai_year

Year number

Returns

true if ai_year is a Leap Year

operator=() [1/3]

const gTime& gTime::operator=

(

const gTime &

timeSrc

)

overload de = operator to assign time values to he object.

Parameters

timeSrc

Time to be assigned

Returns

const gTime& Reference to *this object modified after operation

operator=() [2/3]

const gTime& gTime::operator= ( double  t )

inline

overload the = operator to assign time values to the object in julian days.

Parameters

[in]

t

Time (JD) to be assigned

Returns

const gTime& Reference to *this object modified after operation

operator=() [3/3]

const gTime& gTime::operator=

(

time_t

t

)

overload de = operator to assign time values to he object in time_t (operating system) format.

Parameters

[in]

t

Time to be assigned

Returns

const gTime& Reference to *this object modified after operation

setTime()

void gTime::setTime	(	int	year,
		double	day
	)

Set the time value of the time object to the julian day of year, day.

References:
Astronomical Formulae for Calculators.
Jean Meeus
Chapter 3: Julian Day and Calendar Date. PG's 23, 24, 25

Parameters

[in]	year	date year
[in]	day	date day and day fraction. Notice: 1 Jan is day=0 (not 1)

toThetaGMST()

double gTime::toThetaGMST

(

)

const

Calculate Theta Angle at Greenwich Mean Time for the Julian date.

The return value is the angle, in radians, measuring eastward from the Vernal Equinox to the prime meridian.
References:
Explanatory Supplement to the Astronomical Almanac, page 50. http://books.google.com/books?id=uJ4JhGJANb4C&lpg=PA52&hl=es&pg=PA50#v=onepage&q&f=false "Orbital Coordinate Systems, Part II." Dr. T.Kelzo Satellite Times, 2, no. 2 (November/December 1995): 78-79. https://celestrak.org/columns/v02n02/

Returns

Theta Angle in radians, measuring eastward from the Vernal Equinox to the prime meridian

toThetaLMST()

double gTime::toThetaLMST

(

double

longitude

)

const

Calculate Theta Angle at Local Mean Time for the Julian date.

Parameters

[in]

longitude

Geographical longitude for the local meridian. Positive longitude = east longitude Negative longitude = west longitude

Returns

Theta Angle in radians, measuring eastward from the Vernal Equinox to the prime meridian

toTime()

time_t gTime::toTime

(

)

const

Returns the time_t value of the gTime Object.

Warning

time_t object doesn't support seconds fractions. This method must be avoid for astronomical calculation.

Returns

: time_t machine time represented in the gTime Object