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##

Errorbars

Error bars are supported for 2-d data file plots by reading one to four
additional columns (or **using** entries); these additional values are used in
different ways by the various errorbar styles.
In the default situation, **gnuplot** expects to see three, four, or six
numbers on each line of the data file -- either

(x, y, ydelta),
(x, y, ylow, yhigh),
(x, y, xdelta),
(x, y, xlow, xhigh),
(x, y, xdelta, ydelta), or
(x, y, xlow, xhigh, ylow, yhigh).

The x coordinate must be specified. The order of the numbers must be
exactly as given above, though the **using** qualifier can manipulate the order
and provide values for missing columns. For example,

plot 'file' with errorbars
plot 'file' using 1:2:(sqrt($1)) with xerrorbars
plot 'file' using 1:2:($1-$3):($1+$3):4:5 with xyerrorbars

The last example is for a file containing an unsupported combination of
relative x and absolute y errors. The **using** entry generates absolute x min
and max from the relative error.

The y error bar is a vertical line plotted from (x, ylow) to (x,
yhigh). If ydelta is specified instead of ylow and yhigh, ylow = y -
ydelta and yhigh = y + ydelta are derived. If there are only two
numbers on the record, yhigh and ylow are both set to y. The x error
bar is a horizontal line computed in the same fashion. To get lines
plotted between the data points, **plot** the data file twice, once with
errorbars and once with lines (but remember to use the **notitle**
option on one to avoid two entries in the key). Alternately, use the
errorlines command (see **errorlines (p. )**).

The error bars have crossbars at each end unless **set bars** is used
(see **set bars (p. )** for details).

If autoscaling is on, the ranges will be adjusted to include the error bars.

See also

http://gnuplot.sourceforge.net/demo/mgr.html`errorbar demos.
`

See **plot using (p. )**, **plot with (p. )**, and **set style (p. )** for more information.

** Next:** Errorlines
** Up:** Plot
** Previous:** Zticlabels
** Contents**
** Index**
Ethan Merritt
2007-03-03