Axis 282 Bedienungsanleitung PDF herunterladen (Seite 43)

Chapter II-12 — Graphs

II-275

Selecting a log axis makes the Log Ticks box on the Tick Options tab available:

The “Max log cycles with minor ticks” setting controls whether minor ticks appear on a log axis. This setting

can range from 0 to 20 and defaults to 0. If it is 0 or “auto”, Igor automatically determines if minor ticks are

appropriate. Otherwise, if the axis has more cycles (decades) than this number then the minor ticks are not

displayed. Minor ticks are also not displayed if there is not enough room for them.

Similarly, you can control when Igor puts labels on the minor ticks of a log axis using the Max log cycles

with minor tick labels item. This is a number from 0 to 8; 0 disables the minor tick labels. As long as the axis

has fewer decades than this setting, the minor ticks are labeled.

Manual Ticks

If Igor’s automatic selection of ticks does not suit you, and you can’t find any adjustments

that make the tick marks just the way you want them, Igor provides two methods for

specifying the tick marks yourself. On the Auto/Man Ticks tab of the Modify Axis dialog,

you can choose either Computed Manual Ticks or User Ticks from Waves.

Computed Manual Ticks

Use Computed Manual Ticks to enter a numeric specification of the increment between tick marks and the

starting point for calculating where the tick marks fall. This style of manual ticking is available for normal

axes (including log axes when the loglin checkbox is selected on the Axis tab) and date/time axes only. User

Ticks from Waves can be used to select waves that you have created that completely specify the ticking. This

option is available for normal axes or log axes.

When you choose Computed Manual Ticks the corresponding area of the

Auto/Man Ticks tab becomes available.

If you click the “Set to auto values” button, Igor sets all of the items in the

Compute Manual Ticks box to the values they would have if you let Igor auto-

matically determine the ticking. This is usually the starting point.

Using the “Canonic tick” setting, you specify the value of any major tick mark

on the axis. Using the “Tick increment” setting, you specify the number of axis

units per major tick mark. Both of these numbers are specified as a mantissa

and an exponent. The canonic tick is not necessarily the first major tick on the

axis. Rather, it is a major tick on an infinitely long axis of which the axis in the

graph is a subset. That is, it can be any major tick. whether it shows on the graph or not.

Note: When you use computed manual ticks on a large range logarithmic axis, the values in the dialog

refer to the exponent of the tick value.)

For example, imagine that you want to show the temperature of an object as it cools off. You want to show time

in seconds but you want it to be clear where the integral minutes fall on the axis. You would turn on manual

ticking for the bottom axis and set the canonic tick to zero and the tick increment to 60. You could show the half

and quarter minute points by specifying three minor ticks per major tick (Number per major tick ins the Minor

Ticks box) with every second minor tick emphasized (Emphasize every). This produces the following graph:

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Axis 282 Bedienungsanleitung Seite 43