(maxima.info)Functions and Variables for Runtime Environment
32.3 Functions and Variables for Runtime Environment
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-- System variable: maxima_tempdir
'maxima_tempdir' names the directory in which Maxima creates some
temporary files. In particular, temporary files for plotting are
created in 'maxima_tempdir'.
The initial value of 'maxima_tempdir' is the user's home directory,
if Maxima can locate it; otherwise Maxima makes a guess about a
suitable directory.
'maxima_tempdir' may be assigned a string which names a directory.
-- System variable: maxima_userdir
'maxima_userdir' names a directory which Maxima searches to find
Maxima and Lisp files. (Maxima searches some other directories as
well; 'file_search_maxima' and 'file_search_lisp' are the complete
lists.)
The initial value of 'maxima_userdir' is a subdirectory of the
user's home directory, if Maxima can locate it; otherwise Maxima
makes a guess about a suitable directory.
'maxima_userdir' may be assigned a string which names a directory.
However, assigning to 'maxima_userdir' does not automatically
change 'file_search_maxima' and 'file_search_lisp'; those variables
must be changed separately.
-- Function: room
room ()
room (true)
room (false)
Prints out a description of the state of storage and stack
management in Maxima. 'room' calls the Lisp function of the same
name.
* 'room ()' prints out a moderate description.
* 'room (true)' prints out a verbose description.
* 'room (false)' prints out a terse description.
-- Function: sstatus (<keyword>, <item>)
When <keyword> is the symbol 'feature', <item> is put on the list
of system features. After 'sstatus (keyword, item)' is executed,
'status (feature, item)' returns 'true'. If <keyword> is the
symbol 'nofeature', <item> is deleted from the list of system
features. This can be useful for package writers, to keep track of
what features they have loaded in.
See also 'status'.
-- Function: status
status ('feature')
status ('feature', <item>)
Returns information about the presence or absence of certain
system-dependent features.
* 'status (feature)' returns a list of system features. These
include Lisp version, operating system type, etc. The list
may vary from one Lisp type to another.
* 'status (feature, item)' returns 'true' if <item> is on the
list of items returned by 'status (feature)' and 'false'
otherwise. 'status' quotes the argument <item>. The
quote-quote operator '''' defeats quotation. A feature whose
name contains a special character, such as a hyphen, must be
given as a string argument. For example, 'status (feature,
"ansi-cl")'.
See also 'sstatus'.
The variable 'features' contains a list of features which apply to
mathematical expressions. See 'features' and 'featurep' for more
information.
-- Function: system (<command>)
Executes <command> as a separate process. The command is passed to
the default shell for execution. 'system' is not supported by all
operating systems, but generally exists in Unix and Unix-like
environments.
Supposing '_hist.out' is a list of frequencies which you wish to
plot as a bar graph using 'xgraph'.
(%i1) (with_stdout("_hist.out",
for i:1 thru length(hist) do (
print(i,hist[i]))),
system("xgraph -bar -brw .7 -nl < _hist.out"));
In order to make the plot be done in the background (returning
control to Maxima) and remove the temporary file after it is done
do:
system("(xgraph -bar -brw .7 -nl < _hist.out; rm -f _hist.out)&")
-- Function: time (%o1, %o2, %o3, ...)
Returns a list of the times, in seconds, taken to compute the
output lines '%o1', '%o2', '%o3', ... The time returned is Maxima's
estimate of the internal computation time, not the elapsed time.
'time' can only be applied to output line variables; for any other
variables, 'time' returns 'unknown'.
Set 'showtime: true' to make Maxima print out the computation time
and elapsed time with each output line.
-- Function: timedate
timedate (<T>, <tz_offset>)
timedate (<T>)
timedate ()
'timedate(<T>, <tz_offset>)' returns a string representing the time
<T> in the time zone <tz_offset>. The string format is 'YYYY-MM-DD
HH:MM:SS.NNN[+|-]ZZ:ZZ' (using as many digits as necessary to
represent the fractional part) if <T> has a nonzero fractional
part, or 'YYYY-MM-DD HH:MM:SS[+|-]ZZ:ZZ' if its fractional part is
zero.
<T> measures time, in seconds, since midnight, January 1, 1900, in
the GMT time zone.
<tz_offset> measures the offset of the time zone, in hours, east
(positive) or west (negative) of GMT. <tz_offset> must be an
integer, rational, or float between -24 and 24, inclusive. If
<tz_offset> is not a multiple of 1/60, it is rounded to the nearest
multiple of 1/60.
'timedate(<T>)' is equivalent to 'timedate(<T>, <tz_offset>)' with
<tz_offset> equal to the offset of the local time zone.
'timedate()' is equivalent to 'timedate(absolute_real_time())'.
That is, it returns the current time in the local time zone.
Example:
'timedate' with no argument returns a string representing the
current time and date.
(%i1) d : timedate ();
(%o1) 2010-06-08 04:08:09+01:00
(%i2) print ("timedate reports current time", d) $
timedate reports current time 2010-06-08 04:08:09+01:00
'timedate' with an argument returns a string representing the
argument.
(%i1) timedate (0);
(%o1) 1900-01-01 01:00:00+01:00
(%i2) timedate (absolute_real_time () - 7*24*3600);
(%o2) 2010-06-01 04:19:51+01:00
'timedate' with optional timezone offset.
(%i1) timedate (1000000000, -9.5);
(%o1) 1931-09-09 16:16:40-09:30
-- Function: parse_timedate
parse_timedate (<S>)
Parses a string <S> representing a date or date and time of day and
returns the number of seconds since midnight, January 1, 1900 GMT.
If there is a nonzero fractional part, the value returned is a
rational number, otherwise, it is an integer. 'parse_timedate'
returns 'false' if it cannot parse <S> according to any of the
allowed formats.
The string <S> must have one of the following formats, optionally
followed by a timezone designation:
* 'YYYY-MM-DD[ T]hh:mm:ss[,.]nnn'
* 'YYYY-MM-DD[ T]hh:mm:ss'
* 'YYYY-MM-DD'
where the fields are year, month, day, hours, minutes, seconds, and
fraction of a second, and square brackets indicate acceptable
alternatives. The fraction may contain one or more digits.
Except for the fraction of a second, each field must have exactly
the number of digits indicated: four digits for the year, and two
for the month, day of the month, hours, minutes, and seconds.
A timezone designation must have one of the following forms:
* '[+-]hh:mm'
* '[+-]hhmm'
* '[+-]hh'
* 'Z'
where 'hh' and 'mm' indicate hours and minutes east ('+') or west
('-') of GMT. The timezone may be from +24 hours (inclusive) to -24
hours (inclusive).
A literal character 'Z' is equivalent to '+00:00' and its variants,
indicating GMT.
If no timezone is indicated, the time is assumed to be in the local
time zone.
Any leading or trailing whitespace (space, tab, newline, and
carriage return) is ignored, but any other leading or trailing
characters cause 'parse_timedate' to fail and return 'false'.
See also 'timedate' and 'absolute_real_time'.
Examples:
Midnight, January 1, 1900, in the local time zone, in each
acceptable format. The result is the number of seconds the local
time zone is ahead (negative result) or behind (positive result)
GMT. In this example, the local time zone is 8 hours behind GMT.
(%i1) parse_timedate ("1900-01-01 00:00:00,000");
(%o1) 28800
(%i2) parse_timedate ("1900-01-01 00:00:00.000");
(%o2) 28800
(%i3) parse_timedate ("1900-01-01T00:00:00,000");
(%o3) 28800
(%i4) parse_timedate ("1900-01-01T00:00:00.000");
(%o4) 28800
(%i5) parse_timedate ("1900-01-01 00:00:00");
(%o5) 28800
(%i6) parse_timedate ("1900-01-01T00:00:00");
(%o6) 28800
(%i7) parse_timedate ("1900-01-01");
(%o7) 28800
Midnight, January 1, 1900, GMT, in different indicated time zones.
(%i1) parse_timedate ("1900-01-01 19:00:00+19:00");
(%o1) 0
(%i2) parse_timedate ("1900-01-01 07:00:00+07:00");
(%o2) 0
(%i3) parse_timedate ("1900-01-01 01:00:00+01:00");
(%o3) 0
(%i4) parse_timedate ("1900-01-01Z");
(%o4) 0
(%i5) parse_timedate ("1899-12-31 21:00:00-03:00");
(%o5) 0
(%i6) parse_timedate ("1899-12-31 13:00:00-11:00");
(%o6) 0
(%i7) parse_timedate ("1899-12-31 08:00:00-16:00");
(%o7) 0
-- Function: encode_time
encode_time (<year>, <month>, <day>, <hours>, <minutes>,
<seconds>, <tz_offset>)
encode_time (<year>, <month>, <day>, <hours>, <minutes>,
<seconds>)
Given a time and date specified by <year>, <month>, <day>, <hours>,
<minutes>, and <seconds>, 'encode_time' returns the number of
seconds (possibly including a fractional part) since midnight,
January 1, 1900 GMT.
<year> must be an integer greater than or equal to 1899. However,
1899 is allowed only if the resulting encoded time is greater than
or equal to 0.
<month> must be an integer from 1 to 12, inclusive.
<day> must be an integer from 1 to <n>, inclusive, where <n> is the
number of days in the month specified by <month>.
<hours> must be an integer from 0 to 23, inclusive.
<minutes> must be an integer from 0 to 59, inclusive.
<seconds> must be an integer, rational, or float greater than or
equal to 0 and less than 60. When <seconds> is not an integer,
'encode_time' returns a rational, such that the fractional part of
the return value is equal to the fractional part of <seconds>.
Otherwise, <seconds> is an integer, and the return value is
likewise an integer.
<tz_offset> measures the offset of the time zone, in hours, east
(positive) or west (negative) of GMT. <tz_offset> must be an
integer, rational, or float between -24 and 24, inclusive. If
<tz_offset> is not a multiple of 1/3600, it is rounded to the
nearest multiple of 1/3600.
If <tz_offset> is not present, the offset of the local time zone is
assumed.
See also 'decode_time'.
Examples:
(%i1) encode_time (1900, 1, 1, 0, 0, 0, 0);
(%o1) 0
(%i2) encode_time (1970, 1, 1, 0, 0, 0, 0);
(%o2) 2208988800
(%i3) encode_time (1970, 1, 1, 8, 30, 0, 8.5);
(%o3) 2208988800
(%i4) encode_time (1969, 12, 31, 16, 0, 0, -8);
(%o4) 2208988800
(%i5) encode_time (1969, 12, 31, 16, 0, 1/1000, -8);
2208988800001
(%o5) -------------
1000
(%i6) % - 2208988800;
1
(%o6) ----
1000
-- Function: decode_time
decode_time (<T>, <tz_offset>)
decode_time (<T>)
Given the number of seconds (possibly including a fractional part)
since midnight, January 1, 1900 GMT, returns the date and time as
represented by a list comprising the year, month, day of the month,
hours, minutes, seconds, and time zone offset.
<tz_offset> measures the offset of the time zone, in hours, east
(positive) or west (negative) of GMT. <tz_offset> must be an
integer, rational, or float between -24 and 24, inclusive. If
<tz_offset> is not a multiple of 1/3600, it is rounded to the
nearest multiple of 1/3600.
If <tz_offset> is not present, the offset of the local time zone is
assumed.
See also 'encode_time'.
Examples:
(%i1) decode_time (0, 0);
(%o1) [1900, 1, 1, 0, 0, 0, 0]
(%i2) decode_time (0);
(%o2) [1899, 12, 31, 16, 0, 0, - 8]
(%i3) decode_time (2208988800, 9.25);
37
(%o3) [1970, 1, 1, 9, 15, 0, --]
4
(%i4) decode_time (2208988800);
(%o4) [1969, 12, 31, 16, 0, 0, - 8]
(%i5) decode_time (2208988800 + 1729/1000, -6);
1729
(%o5) [1969, 12, 31, 18, 0, ----, - 6]
1000
(%i6) decode_time (2208988800 + 1729/1000);
1729
(%o6) [1969, 12, 31, 16, 0, ----, - 8]
1000
-- Function: absolute_real_time ()
Returns the number of seconds since midnight, January 1, 1900 GMT.
The return value is an integer.
See also 'elapsed_real_time' and 'elapsed_run_time'.
Example:
(%i1) absolute_real_time ();
(%o1) 3385045277
(%i2) 1900 + absolute_real_time () / (365.25 * 24 * 3600);
(%o2) 2007.265612087104
-- Function: elapsed_real_time ()
Returns the number of seconds (including fractions of a second)
since Maxima was most recently started or restarted. The return
value is a floating-point number.
See also 'absolute_real_time' and 'elapsed_run_time'.
Example:
(%i1) elapsed_real_time ();
(%o1) 2.559324
(%i2) expand ((a + b)^500)$
(%i3) elapsed_real_time ();
(%o3) 7.552087
-- Function: elapsed_run_time ()
Returns an estimate of the number of seconds (including fractions
of a second) which Maxima has spent in computations since Maxima
was most recently started or restarted. The return value is a
floating-point number.
See also 'absolute_real_time' and 'elapsed_real_time'.
Example:
(%i1) elapsed_run_time ();
(%o1) 0.04
(%i2) expand ((a + b)^500)$
(%i3) elapsed_run_time ();
(%o3) 1.26
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