issues: "Nonlinear tting is an art!"

Help

The help command displays built-in help. To specify information on a particular topic use the syntax:

help {<topic>}

If <topic> is not speci ed, a short message is printed about gnuplot. After help for the requested topic is given, a menu of subtopics is given; help for a subtopic may be requested by typing its name, extending the help request. After that subtopic has been printed, the request may be extended again or you may go back one level to the previous topic. Eventually, the gnuplot command line will return.

If a question mark (?) is given as the topic, the list of topics currently available is printed on the screen.

History

history command lists or saves previous entries in the history of the command line editing, or executes an entry.

Here you nd 'usage by examples':

history 10 "|head -5 >>diary.gp" # write 5 history commands using pipe

On systems which support a popen function (Unix), the output of history can be piped through an external program by starting the le name with a 'j', as one of the above examples demonstrates.

If

New syntax:

if (<condition>) { <command>; <command> <commands>

<commands> } else {

<commands>

}

Old syntax:

if (<condition>) <command-line> [; else if (<condition>) ...; else ...]

This version of gnuplot supports block-structured if/else statements. If the keyword if or else is immediately followed by an opening "f", then conditional execution applies to all statements, possibly on multiple input lines, until a matching "g" terminates the block. If commands may be nested.

The old single-line if/else syntax is still supported, but can not be mixed with the new block-structured syntax. See if-old (p. 70).

If-old

Through gnuplot version 4.4, the scope of the if/else commands was limited to a single input line. This has been replaced by allowing a multi-line clause to be enclosed in curly brackets. The old syntax is still honored by itself but cannot be used inside a bracketed clause.

If no opening "f" follows the if keyword, the command(s) in <command-line> will be executed if <condition> is true (non-zero) or skipped if <condition> is false (zero). Either case will consume commands on the input line until the end of the line or an occurrence of else. Note that use of ; to allow multiple commands on the same line will not end the conditionalized commands.

Examples:

pi=3

if (pi!=acos(-1)) print "?Fixing pi!"; pi=acos(-1); print pi

will display:

?Fixing pi! 3.14159265358979

but

if (1==2) print "Never see this"; print "Or this either"

will not display anything.

else:

v=0

v=v+1; if (v%2) print "2" ; else if (v%3) print "3"; else print "fred"

(repeat the last line repeatedly!)

See reread (p. 94) for an example of using if and reread together to perform a loop.

Iteration

The plot, splot, set and unset commands may optionally contain an iteration clause. This has the e ect of executing the basic command multiple times, each time re-evaluating any expressions that make use of the iteration control variable. Iteration of arbitrary command sequences can be requested using the do command. Two forms of iteration clause are currently supported:

for [intvar = start:end{:increment}] for [stringvar in "A B C D"]

Examples:

plot for [filename in "A.dat B.dat C.dat"] filename using 1:2 with lines plot for [basename in "A B C"] basename.".dat" using 1:2 with lines

set for [i = 1:10] style line i lc rgb "blue" unset for [tag = 100:200] label tag

Nested iteration is supported:

set for [i=1:9] for [j=1:9] label i*10+j sprintf("%d",i*10+j) at i,j

See additional documentation for plot iteration (p. 88), do (p. 61).

Load

The load command executes each line of the speci ed input le as if it had been typed in interactively. Files created by the save command can later be loaded. Any text le containing valid commands can be created and then executed by the load command. Files being loaded may themselves contain load or call commands. See comments (p. 22) for information about comments in commands. To load with arguments, see call (p. 60).

Syntax:

load "<input-file>"

The name of the input le must be enclosed in quotes.

The special lename "-" may be used to load commands from standard input. This allows a gnuplot command le to accept some commands from standard input. Please see help for batch/interactive (p. 20) for more details.

On some systems which support a popen function (Unix), the load le can be read from a pipe by starting the le name with a '<'.

Examples:

load 'work.gnu' load "func.dat"

load "< loadfile_generator.sh"

The load command is performed implicitly on any le names given as arguments to gnuplot. These are loaded in the order speci ed, and then gnuplot exits.

Lower

Syntax:

lower {plot_window_nb}

The lower command lowers (opposite to raise) plot window(s) associated with the interactive terminal of your gnuplot session, i.e. pm, win, wxt or x11. It puts the plot window to bottom in the z-order windows stack of the window manager of your desktop.

As x11 and wxt support multiple plot windows, then by default they lower these windows in descending order of most recently created on top to the least recently created on bottom. If a plot number is supplied as an optional parameter, only the associated plot window will be lowered if it exists.

The optional parameter is ignored for single plot-window terminals, i.e. pm and win.

Pause

The pause command displays any text associated with the command and then waits a speci ed amount of time or until the carriage return is pressed. pause is especially useful in conjunction with load les.

Syntax:

pause <time> {"<string>"}

pause mouse {<endcondition>}{, <endcondition>} {"<string>"}

<time> may be any constant or expression. Choosing -1 will wait until a carriage return is hit, zero (0) won't pause at all, and a positive number will wait the speci ed number of seconds. The time is rounded to an integer number of seconds if subsecond time resolution is not supported by the given platform. pause 0 is synonymous with print.

If the current terminal supports mousing, then pause mouse will terminate on either a mouse click or on ctrl-C. For all other terminals, or if mousing is not active, pause mouse is equivalent to pause -1.

If one or more end conditions are given after pause mouse, then any one of the conditions will terminate the pause. The possible end conditions are keypress, button1, button2, button3, close, and any. If the pause terminates on a keypress, then the ascii value of the key pressed is returned in MOUSE KEY. The character itself is returned as a one character string in MOUSE CHAR. Hotkeys (bind command) are disabled if keypress is one of the end conditions. Zooming is disabled if button3 is one of the end conditions.

In all cases the coordinates of the mouse are returned in variables MOUSE X, MOUSE Y, MOUSE X2, MOUSE Y2. See mouse variables (p. 37).

Note: Since pause communicates with the operating system rather than the graphics, it may behave di erently with di erent device drivers (depending upon how text and graphics are mixed).

Examples: