Octave’s core set of functions for manipulating time values are patterned after the corresponding functions from the standard C library. Several of these functions use a data structure for time that includes the following elements:
usecMicroseconds after the second (0-999999).
secSeconds after the minute (0-60). This number can be 60 to account for leap seconds.
minMinutes after the hour (0-59).
hourHours since midnight (0-23).
mdayDay of the month (1-31).
monMonths since January (0-11).
yearYears since 1900.
wdayDays since Sunday (0-6).
ydayDays since January 1 (0-365).
isdstDaylight saving time flag.
gmtoffSeconds offset from UTC.
zoneTime zone.
In the descriptions of the following functions, this structure is referred to as a tm_struct.
seconds = time () ¶Return the current time as the number of seconds since the epoch.
The epoch is referenced to 00:00:00 UTC (Coordinated Universal Time) 1 Jan
1970. For example, on Monday February 17, 1997 at 07:15:06 UTC, the value
returned by time was 856163706.
See also: strftime, strptime, localtime, gmtime, mktime, now, date, clock, datenum, datestr, datevec, calendar, weekday.
t = now () ¶Return the current local date/time as a serial day number
(see datenum).
The integral part, floor (now) corresponds to the number of days
between today and Jan 1, 0000.
The fractional part, rem (now, 1) corresponds to the current time.
str = ctime (t) ¶Convert a value returned from time (or any other non-negative
integer), to the local time and return a string of the same form as
asctime.
The function ctime (time) is equivalent to
asctime (localtime (time)). For example:
ctime (time ()) ⇒ "Mon Feb 17 01:15:06 1997\n"
tm_struct = gmtime (t) ¶Given a value returned from time, or any non-negative integer,
return a time structure corresponding to UTC (Coordinated Universal Time).
For example:
gmtime (time ())
⇒ {
usec = 0
sec = 6
min = 15
hour = 7
mday = 17
mon = 1
year = 97
wday = 1
yday = 47
isdst = 0
gmtoff = 0
zone = GMT
}
See also: strftime, strptime, localtime, mktime, time, now, date, clock, datenum, datestr, datevec, calendar, weekday.
tm_struct = localtime (t) ¶Given a value returned from time, or any non-negative integer,
return a time structure corresponding to the local time zone.
localtime (time ())
⇒ {
usec = 0
sec = 6
min = 15
hour = 1
mday = 17
mon = 1
year = 97
wday = 1
yday = 47
isdst = 0
gmtoff = -21600
zone = CST
}
See also: strftime, strptime, gmtime, mktime, time, now, date, clock, datenum, datestr, datevec, calendar, weekday.
seconds = mktime (tm_struct) ¶Convert a time structure corresponding to the local time to the number of seconds since the epoch.
For example:
mktime (localtime (time ()))
⇒ 856163706
See also: strftime, strptime, localtime, gmtime, time, now, date, clock, datenum, datestr, datevec, calendar, weekday.
str = asctime (tm_struct) ¶Convert a time structure to a string using the following
format: "ddd mmm mm HH:MM:SS yyyy\n".
For example:
asctime (localtime (time ()))
⇒ "Mon Feb 17 01:15:06 1997\n"
This is equivalent to ctime (time ()).
str = strftime (fmt, tm_struct) ¶Format the time structure tm_struct in a flexible way using the format
string fmt that contains ‘%’ substitutions similar to those in
printf.
Except where noted, substituted fields have a fixed size; numeric fields are padded if necessary. Padding is with zeros by default; for fields that display a single number, padding can be changed or inhibited by following the ‘%’ with one of the modifiers described below. Unknown field specifiers are copied as normal characters. All other characters are copied to the output without change. For example:
strftime ("%r (%Z) %A %e %B %Y", localtime (time ()))
⇒ "01:15:06 AM (CST) Monday 17 February 1997"
Octave’s strftime function supports a superset of the ANSI C field
specifiers.
Literal character fields:
%%% character.
%nNewline character.
%tTab character.
Numeric modifiers (a nonstandard extension):
- (dash)Do not pad the field.
_ (underscore)Pad the field with spaces.
Time fields:
%HHour (00-23).
%IHour (01-12).
%kHour (0-23).
%lHour (1-12).
%MMinute (00-59).
%pLocale’s AM or PM.
%rTime, 12-hour (hh:mm:ss [AP]M).
%RTime, 24-hour (hh:mm).
%sTime in seconds since 00:00:00, Jan 1, 1970 (a nonstandard extension).
%SSecond (00-61).
%TTime, 24-hour (hh:mm:ss).
%XLocale’s time representation (%H:%M:%S).
%zOffset from UTC (±hhmm), or nothing if no time zone is determinable.
%ZTime zone (EDT), or nothing if no time zone is determinable.
Date fields:
%aLocale’s abbreviated weekday name (Sun-Sat).
%ALocale’s full weekday name, variable length (Sunday-Saturday).
%bLocale’s abbreviated month name (Jan-Dec).
%BLocale’s full month name, variable length (January-December).
%cLocale’s date and time (Sat Nov 04 12:02:33 EST 1989).
%CCentury (00-99).
%dDay of month (01-31).
%eDay of month ( 1-31).
%DDate (mm/dd/yy).
%hSame as %b.
%jDay of year (001-366).
%mMonth (01-12).
%UWeek number of year with Sunday as first day of week (00-53).
%wDay of week (0-6).
%WWeek number of year with Monday as first day of week (00-53).
%xLocale’s date representation (mm/dd/yy).
%yLast two digits of year (00-99).
%YYear (1970-).
See also: strptime, localtime, gmtime, mktime, time, now, date, clock, datenum, datestr, datevec, calendar, weekday.
[tm_struct, nchars] = strptime (str, fmt) ¶Convert the string str to the time structure tm_struct under the control of the format string fmt.
If fmt fails to match, nchars is 0; otherwise, it is set to the position of last matched character plus 1. Always check for this unless you’re absolutely sure the date string will be parsed correctly.
See also: strftime, localtime, gmtime, mktime, time, now, date, clock, datenum, datestr, datevec, calendar, weekday.
Most of the remaining functions described in this section are not patterned after the standard C library. Some are available for compatibility with MATLAB and others are provided because they are useful.
datevec = clock () ¶[datevec, isdst] = clock () ¶Return the current local date and time as a date vector.
The date vector contains the following fields: current year, month (1-12), day (1-31), hour (0-23), minute (0-59), and second (0-61). The seconds field has a fractional part after the decimal point for extended accuracy.
The optional second output isdst is true if Daylight Savings Time (DST) is in effect for the system’s time zone.
For example:
fix (clock ()) ⇒ 1993 8 20 4 56 1
clock is more accurate on systems that have the gettimeofday
function.
str = date () ¶Return the current date as a character string in the form DD-MMM-YYYY.
For example:
date () ⇒ 20-Aug-1993
secs = etime (t2, t1) ¶Return the difference in seconds between two time values returned from
clock (t2 - t1).
For example:
t0 = clock (); # many computations later… elapsed_time = etime (clock (), t0);
will set the variable elapsed_time to the number of seconds since the
variable t0 was set.
[total, user, system] = cputime (); ¶Return the CPU time used by your Octave session.
The first output is the total time spent executing your process and is equal to the sum of second and third outputs, which are the number of CPU seconds spent executing in user mode and the number of CPU seconds spent executing in system mode, respectively.
If your system does not have a way to report CPU time usage, cputime
returns 0 for each of its output values.
Note that because Octave used some CPU time to start, it is reasonable
to check to see if cputime works by checking to see if the total
CPU time used is nonzero.
tf = is_leap_year () ¶tf = is_leap_year (year) ¶Return true if year is a leap year and false otherwise.
If no year is specified, is_leap_year uses the current year.
For example:
is_leap_year (2000) ⇒ 1
() ¶id = tic () ¶Initialize a wall-clock timer.
Calling tic without an output argument resets the internal timer.
Subsequent calls to toc return the number of seconds since the timer was
set.
If called with one output argument, tic creates a new timer instance and
returns a timer identifier id. The id is a scalar of type
uint64 that may be passed to toc to check elapsed time on this
timer, rather than the default internal timer.
Example 1 : benchmarking code with internal timer
tic; # many computations later… elapsed_time = toc;
Example 2 : mixed timer id and internal timer
tic; pause (1); toc ⇒ Elapsed time is 1.0089 seconds. id = tic; pause (2); toc (id) ⇒ Elapsed time is 2.01142 seconds. toc Elapsed time is 3.02308 seconds.
Calling tic and toc in this way allows nested timing calls.
If you are more interested in the CPU time that your process used, you should
use the cputime function instead. The tic and toc
functions report the actual wall clock time that elapsed between the calls.
This may include time spent processing other jobs or doing nothing at all.
() ¶(id) ¶elapsed_time = toc (…) ¶Measure elapsed time on a wall-clock timer.
With no arguments, return the number of seconds elapsed on the internal timer
since the last call to tic.
When given the identifier id of a specific timer, return the number of seconds elapsed since the timer id was initialized.
See tic, for examples of the use of tic/toc.
() ¶(n) ¶old_state = pause ("on") ¶old_state = pause ("off") ¶old_state = pause ("query") ¶Suspend the execution of the program or change the state of the pause function.
If invoked without an input arguments then the program is suspended until a character is typed. If argument n is a positive real value, it indicates the number of seconds the program shall be suspended, for example:
tic; pause (0.05); toc
-| Elapsed time is 0.05039 seconds.
The following example prints a message and then waits 5 seconds before clearing the screen.
disp ("wait please...");
pause (5);
clc;
If invoked with a string argument "on", "off", or
"query", the state of the pause function is changed or queried. When
the state is "off", the pause function returns immediately. The
optional return value contains the previous state of the pause function. In
the following example pause is disabled locally:
old_state = pause ("off");
tic; pause (0.05); toc
-| Elapsed time is 3.00407e-05 seconds.
pause (old_state);
While the program is suspended Octave still handles figures painting and graphics callbacks execution.
See also: kbhit.
days = datenum (datevec) ¶days = datenum (year, month, day) ¶days = datenum (year, month, day, hour) ¶days = datenum (year, month, day, hour, minute) ¶days = datenum (year, month, day, hour, minute, second) ¶days = datenum ("datestr") ¶days = datenum ("datestr", f) ¶days = datenum ("datestr", p) ¶[days, secs] = datenum (…) ¶Return the date/time input as a serial day number, with Jan 1, 0000 defined as day 1.
The integer part, floor (days) counts the number of
complete days in the date input.
The fractional part, rem (days, 1) corresponds to the time
on the given day.
The input may be a date vector (see datevec),
date string (see datestr), or directly specified
as input.
When processing input datestrings, f is the format string used to
interpret date strings (see datestr). If no
format f is specified, then a relatively slow search is performed
through various formats. It is always preferable to specify the format
string f if it is known. Formats which do not specify a particular
time component will have the value set to zero. Formats which do not
specify a date will default to January 1st of the current year.
When passing separate year, month, day, etc. arguments, each may be a scalar or nonscalar array. Nonscalar inputs must all be of the same size. Scalar inputs will be expanded to be the size of the nonscalar inputs.
p is the year at the start of the century to which two-digit years will be referenced. If not specified, it defaults to the current year minus 50.
The optional output secs holds the time on the specified day with greater precision than days.
Notes:
Examples:
Convert from datestrs:
d = datenum ("1966-06-14")
⇒ d = 718232
d = datenum ({"1966-06-14", "1966-06-15", "1966-06-16"})
⇒ d =
718232
718233
718234
Convert from datevec: d = datenum ([1966 06 14]) ⇒ d = 718232
d = datenum ([1966 06 14 23 59 59]) ⇒ d = 718232.9999884259
Specify date components separately: d = datenum (1966, 6, 14) ⇒ d = 718232
d = datenum (1966, magic(3), 1)
⇒ d =
718280 718068 718219
718127 718188 718249
718158 718311 718099
Caution: datenums represent a specific time for the Earth as a
whole. They do not take in to account time zones (shifts in time based
on location), nor seasonal changes due to Daylight Savings Time (shifts in
time based on local regulation). Be aware that it is possible to create
datenums that, when interpreted by a function which accounts for time zone
and DST shifts such as datestr, are nonexistent or ambiguous.
Caution: this function does not attempt to handle Julian calendars so dates before October 15, 1582 are wrong by as much as eleven days. Also, be aware that only Roman Catholic countries adopted the calendar in 1582. It took until 1924 for it to be adopted everywhere. See the Wikipedia entry on the Gregorian calendar for more details.
Warning: leap seconds are ignored. A table of leap seconds is available on the Wikipedia entry for leap seconds.
Algorithm: Peter Baum (http://vsg.cape.com/~pbaum/date/date0.htm)
str = datestr (date) ¶str = datestr (date, f) ¶str = datestr (date, f, p) ¶Format the given date/time according to the format f and return the result in str.
date is a serial date number (see datenum), a
date vector (see datevec), or a string or cell array
of strings. In the latter case, it is passed to datevec to guess the
input date format.
f can be an integer which corresponds to one of the codes in the table below, or a date format string.
p is the year at the start of the century in which two-digit years are to be interpreted in. If not specified, it defaults to the current year minus 50.
For example, the date 730736.65149 (2000-09-07 15:38:09.0934) would be formatted as follows:
| Code | Format | Example |
|---|---|---|
| 0 | dd-mmm-yyyy HH:MM:SS | 07-Sep-2000 15:38:09 |
| 1 | dd-mmm-yyyy | 07-Sep-2000 |
| 2 | mm/dd/yy | 09/07/00 |
| 3 | mmm | Sep |
| 4 | m | S |
| 5 | mm | 09 |
| 6 | mm/dd | 09/07 |
| 7 | dd | 07 |
| 8 | ddd | Thu |
| 9 | d | T |
| 10 | yyyy | 2000 |
| 11 | yy | 00 |
| 12 | mmmyy | Sep00 |
| 13 | HH:MM:SS | 15:38:09 |
| 14 | HH:MM:SS PM | 3:38:09 PM |
| 15 | HH:MM | 15:38 |
| 16 | HH:MM PM | 3:38 PM |
| 17 | QQ-YY | Q3-00 |
| 18 | Q3 | |
| 19 | dd/mm | 07/09 |
| 20 | dd/mm/yy | 07/09/00 |
| 21 | mmm.dd,yyyy HH:MM:SS | Sep.07,2000 15:38:08 |
| 22 | mmm.dd,yyyy | Sep.07,2000 |
| 23 | mm/dd/yyyy | 09/07/2000 |
| 24 | dd/mm/yyyy | 07/09/2000 |
| 25 | yy/mm/dd | 00/09/07 |
| 26 | yyyy/mm/dd | 2000/09/07 |
| 27 | QQ-YYYY | Q3-2000 |
| 28 | mmmyyyy | Sep2000 |
| 29 | yyyy-mm-dd | 2000-09-07 |
| 30 | yyyymmddTHHMMSS | 20000907T153808 |
| 31 | yyyy-mm-dd HH:MM:SS | 2000-09-07 15:38:08 |
If f is a format string, the following symbols are recognized:
| Symbol | Meaning | Example |
|---|---|---|
| yyyy | Full year | 2005 |
| yy | Two-digit year | 05 |
| mmmm | Full month name | December |
| mmm | Abbreviated month name | Dec |
| mm | Numeric month number (padded with zeros) | 01, 08, 12 |
| m | First letter of month name (capitalized) | D |
| dddd | Full weekday name | Sunday |
| ddd | Abbreviated weekday name | Sun |
| dd | Numeric day of month (padded with zeros) | 11 |
| d | First letter of weekday name (capitalized) | S |
| HH | Hour of day, padded with zeros, | 09:00 |
| or padded with spaces if PM is set | 9:00 AM | |
| MM | Minute of hour (padded with zeros) | 10:05 |
| SS | Second of minute (padded with zeros) | 10:05:03 |
| FFF | Milliseconds of second (padded with zeros) | 10:05:03.012 |
| AM | Use 12-hour time format | 11:30 AM |
| PM | Use 12-hour time format | 11:30 PM |
If f is not specified or is -1, then use 0, 1 or 16, depending
on whether the date portion or the time portion of date is empty.
If p is not specified, it defaults to the current year minus 50.
If a matrix or cell array of dates is given, a column vector of date strings is returned.
v = datevec (date) ¶v = datevec (date, f) ¶v = datevec (date, p) ¶v = datevec (date, f, p) ¶[y, m, d, h, mi, s] = datevec (…) ¶Convert a serial date number (see datenum) or date
string (see datestr) into a date vector.
A date vector is a row vector with six members, representing the year, month, day, hour, minute, and seconds respectively.
Date number inputs can be either a scalar or nonscalar array. Date string inputs can be either a single date string, a two-dimensional character array of dates with each row being an interpretable date string, or a cell string array of any dimension with each cell element containing a single interpretable date string.
v is a two-dimensional array of date vectors, one date vector per row. For array inputs, ordering of v is based on column major order of dates in data.
f is the format string used to interpret date strings
(see datestr). If date is a string or a cell
array of strings, but no format is specified, heuristics are used to guess
the input format. These heuristics could lead to matches that differ from
the result a user might expect. Additionally, this involves a relatively
slow search through various formats. It is always preferable to specify
the format string f if it is known. Formats which do not specify a
particular time component will have the value set to zero. Formats which
do not specify a particular date component will default that component to
January 1st of the current year.
p is the year at the start of the century to which two-digit years will be referenced. If not specified, it defaults to the current year minus 50.
d = addtodate (d, q, f) ¶Add q amount of time (with units f) to the serial datenum, d.
f must be one of "year", "month", "day",
"hour", "minute", "second", or
"millisecond".
c = calendar () ¶c = calendar (d) ¶c = calendar (y, m) ¶(…) ¶Return the current monthly calendar in a 6x7 matrix.
If d is specified, return the calendar for the month containing the date d, which must be a serial date number or a date string.
If y and m are specified, return the calendar for year y and month m.
If no output arguments are specified, print the calendar on the screen instead of returning a matrix.
[n, s] = weekday (d) ¶[n, s] = weekday (d, format) ¶Return the day of the week as a number in n and as a string in s.
The days of the week are numbered 1–7 with the first day being Sunday.
d is a serial date number or a date string.
If the string format is not present or is equal to "short"
then s will contain the abbreviated name of the weekday. If
format is "long" then s will contain the full name.
Table of return values based on format:
| n | "short" | "long" |
|---|---|---|
| 1 | Sun | Sunday |
| 2 | Mon | Monday |
| 3 | Tue | Tuesday |
| 4 | Wed | Wednesday |
| 5 | Thu | Thursday |
| 6 | Fri | Friday |
| 7 | Sat | Saturday |
See also: eomday, is_leap_year, calendar, datenum, datevec.
e = eomday (y, m) ¶Return the last day of the month m for the year y.
See also: weekday, datenum, datevec, is_leap_year, calendar.
() ¶(axis_str) ¶(date_format) ¶(axis_str, date_format) ¶(…, "keeplimits") ¶(…, "keepticks") ¶(hax, …) ¶Add date-formatted tick labels to an axis.
The axis to apply the ticks to is determined by axis_str which can
take the values "x", "y", or "z". The default
value is "x".
The formatting of the labels is determined by the variable
date_format, which can either be a string or positive integer that
datestr accepts.
If the first argument hax is an axes handle, then plot into this axes,
rather than the current axes returned by gca.