Axis 282 Uživatelský manuál stáhnout pdf (Strana 31)

Chapter II-12 — Graphs

II-263

You can control this using the Gaps checkbox in the Modify Trace Appearance dialog. If this checkbox is

selected (the default), Igor shows missing values as gaps in the data. If you deselect this checkbox, Igor

ignores missing values, connecting the available data points on either side of the missing value.

Error Bars

The Error Bars checkbox adds error bars to the selected trace. When you select this checkbox, Igor presents

the Error Bars subdialog.

Error bars are a style that you can add to a trace in a graph. Error values can be a constant number, a fixed

percent of the value of the wave at the given point, the square root of the value of the wave at the given

point, or they can be arbitrary values taken from other waves. In this last case, the error values can be set

independently for the up, down, left and right directions. See the ErrorBars operation on page V-146 for an

illustration of the names for the various parts of error bars.

Choose the desired mode from the “Y Error bars” and “X Error bars” pop-up menus.

The dialog changes depending on the selected mode. For the “% of base” mode, you enter the percent of the

base wave. For the “sqrt of base” mode, you don’t need to enter any further values. This mode is meaningful

only when your data is in counts. For the “constant” mode, you enter the constant error value for the X or Y

direction. For the “+/- wave” mode, you select the waves to supply the positive and negative error values.

If you select “+/- wave”, pop-up menus appear from which you can choose the waves to supply the upper

and lower or left and right error values, These waves are called error waves. The values in error waves

should normally all be positive since they specify the length of the line from each point to its error bar. This

is the only mode that supports single-sided error bars. Error waves do not have to have the same numeric

type and length as the base wave. If the value of a point in an error wave is NaN then the error bar corre-

sponding to that point is not drawn.

1.2

1.0

0.8

0.6

0.4

0.2

0.0

1.00.80.60.40.20.0

Gaps

No Gaps

Select error waves that are

the same length or greater

than the base. For a longer

error wave, the Subrange

button becomes available so

that you can select a specific

point range from the wave.

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Axis 282 Uživatelský manuál Strana 31