## 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.

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 during datafile manipulation.
columnhead(x) | int | string containing first entry of column in datafile.
exists("X") | string | returns 1 if a variable named X is defined, 0 otherwise.
hsv2rgb(h,s,v) | h,s,v [0:1] | 24bit RGB color value.
palette(z) | double | RGB palette color mapped to z.
stringcolumn(x) | int or string | content of column as a string.
timecolumn(N,"timeformat") | int, string | time data from column 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 during datafile manip.
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)

Subsections

- Elliptic integrals
- Random number generator
- Value
- Counting and extracting words