Axis 282 Bedienungsanleitung PDF herunterladen (Seite 37)

Chapter II-12 — Graphs

II-269

Ticks and Grids Tab

The Ticks and Grids tab has items to control the appearance of ticks and to select and control graph grids:

Exponential Labels

When numbers that would be used to label tick marks become very large or very small, Igor switches to

exponential notation. For example if the tick values for an axis are 0, 1000000000, 2000000000, 3000000000,

and 4000000000 then Igor will break the values into a small number and an exponent. In this case Igor

would choose 0,1,2,3 and 4 with the exponent being 10

. Igor uses the small numbers to label the tick marks

and leaves the exponent for your use in the axis label. The use of the exponent in the axis label is covered

in the Axis Labels section on page 282. In the case of log axes, the tick marks include the exponent part.

With the Low trip and High trip settings, you can control the point at which tick mark labels switch from

normal notation to exponential notation. If the absolute value of the larger end of the axis is between the

low trip and the high trip, then normal notation is used. Otherwise, exponential is used. However, if the

exponent would be zero, normal notation is always used.

There are actually two independent sets of low trip and high trip parameters: one for normal axes and one

for log axes. The low trip point can be from 1e-38 to 1 and defaults to 0.1 for normal axes and to 1e-4 for log

axes. The high trip point can be from 1 to 1e38 and defaults to 1e4.

Under some circumstances, Igor may not honor your setting of these trip points. If there is no room for

normal tick mark labels, Igor will use exponential notation, even if you have requested normal notation.

The Engineering and Scientific radio buttons allow you to specify whether tick mark labels should use engi-

neering or scientific notation when exponential notation is used. It does not affect log axes. Engineering

mode is just exponential notation where the exponent is always a multiple of three.

With the Exponent Prescale item, you can force the tick and axis label scaling to values different from what

Igor would pick. For example, if you have data whose x scaling ranges from, say, 9pA to 120pA and you

display this on a log axis, Igor will label the tick marks with 10pA and 100pA. But if you really want the tick

marks labeled 10 and 100 with pA in the axis label, you can set the prescaleExp to 12. For details, see Axis

Labels on page II-282.

Date/Time Tick Labels

The Date/Time Tick Labels area of the tab is explained in the Date/Time Axes section on page 278.

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Axis 282 Bedienungsanleitung Seite 37