Functions

Arguments to math functions in gnuplot can be integer, real, or complex unless otherwise noted. Functions that accept or return angles (e.g. sin(x)) treat angle values as radians, but this may be changed to degrees using the command set angles.

11#11

12#12

String functions
Function	Arguments	Returns
gprintf("format",x,...)	any	string result from applying gnuplot's format parser
sprintf("format",x,...)	multiple	string result from C-language sprintf
strlen("string")	string	number of characters in string
strstrt("string","key")	strings	int index of first character of substring "key"
substr("string",beg,end)	multiple	string "string"[beg:end]
strftime("timeformat",t)	any	string result from applying gnuplot's time parser
strptime("timeformat",s)	string	seconds since year 1970 as given in string s
system("command")	string	string containing output stream of shell command
trim(" string ")	string	string without leading or trailing whitespace
word("string",n)	string, int	returns the nth word in "string"
words("string")	string	returns the number of words in "string"

other gnuplot functions
Function	Arguments	Returns
column(x)	int or string	column 13#13 during datafile input
columnhead(x)	int	string containing first entry of column 13#13 in datafile.
exists("X")	string	returns 1 if a variable named X is defined, 0 otherwise.
hsv2rgb(h,s,v)	h,s,v 14#14 [0:1]	24bit RGB color value.
palette(z)	double	RGB palette color mapped to z.
stringcolumn(x)	int or string	content of column 13#13 as a string.
timecolumn(N,"timeformat")	int, string	time data from column 15#15 during data input.
tm_hour(t)	time in sec	the hour (0..23)
tm_mday(t)	time in sec	the day of the month (1..31)
tm_min(t)	time in sec	the minute (0..59)
tm_mon(t)	time in sec	the month (0..11)
tm_sec(t)	time in sec	the second (0..59)
tm_wday(t)	time in sec	the day of the week (Sun..Sat) as (0..6)
tm_week(t)	time in sec	week of year in ISO8601 "week date" system (1..53)
tm_yday(t)	time in sec	the day of the year (0..365)
tm_year(t)	time in sec	the year
time(x)	any	the current system time in seconds
valid(x)	int	test validity of 16#16 during datafile input
value("name")	string	returns the value of the named variable.
voxel(x,y,z)	real	value of the active grid voxel containing point (x,y,z)