Time and Calendar functions

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GAMS contains a number of functions that may be used to do things involved with times and dates. The fundamental measurement of time in GAMS is the sequential day number since January 1, 1900, where the integer part of this number contains a unique number for each day while the fractional part contains information about hour, minute, second etc. The day numbers are based on the Gregorian calendar.

In the following table the Endogenous Classification (second column) specifies in which models the function can legally appear. In order of least to most restrictive, the choices are any, NLP, DNLP or none. Note that constant arguments are required.

 

 

Function

Endogenous

Classification

Description

gday(SDAY)

any

returns Gregorian day from a serial day number date.time, where Jan 1, 1900 is day 1

gdow(SDAY)

any

returns Gregorian day of week from a serial day number date.time, where Jan 1, 1900 is day 1

ghour(SDAY)

any

returns Gregorian hour of day from a serial day number date.time, where Jan 1, 1900 is day 1

gleap(SDAY)

any

returns 1 if the year that corresponds to a serial day number date.time, where Jan 1, 1900 is day 1, is a leap year, else returns 0

gmillisec(SDAY)

any

returns Gregorian milli second from a serial day number date.time, where Jan 1, 1900 is day 1

gminute(SDAY)

any

returns Gregorian minute of hour from a serial day number date.time, where Jan 1, 1900 is day 1

gmonth(SDAY)

any

returns Gregorian month from a serial day number date.time, where Jan 1, 1900 is day 1

gsecond(SDAY)

any

returns Gregorian second of minute from a serial day number date.time, where Jan 1, 1900 is day 1

gyear(SDAY)

any

returns Gregorian year from a serial day number date.time, where Jan 1, 1900 is day 1

jdate(YEAR,MONTH,DAY)

any

returns a serial day number, starting with Jan 1, 1900 as day 1

jnow

none

returns the current time as a serial day number, starting with Jan 1, 1900 as day 1

jstart

none

returns the time of the start of the GAMS job as a serial day number, starting with Jan 1, 1900 as day 1

jtime(HOUR,MIN,SEC)

any

returns fraction of a day that corresponds to hour, minute and second

 

 

Example:

(mycalendar.gms)

todaydate  = jstart;

now    = jnow;

year   = gyear(todaydate);

month  = gmonth (todaydate);

day    = gday   (todaydate);

hour   = ghour(todaydate);

minute = gminute(todaydate);

second = gsecond(todaydate);

dow    = gdow (todaydate);

leap   = gleap(todaydate);

display todaydate,now, year, month, day, hour, minute, second, dow, leap;

 

date  = jdate(year,month,day);

time  = jtime(hour,minute,second);

display date,time;

 

scalar plus200days;

todaydate  = jstart+200;

year   = gyear(todaydate);

month  = gmonth (todaydate);

day    = gday   (todaydate);

display todaydate,year, month, day;