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Usage of Newton in detail
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expression at the cursor position. The selected edit field is denoted by its caption., which is
displayed in bold characters.
After entering the expression you should verify that it is acceptable for the program. Click on
the Syntax Check button. If an error is found, Newton will present an error message and the
edit field of the wrong expression will turn to red. A syntax check will be carried out
automatically after you click the OK button of the dialog. You cannot close the dialogs as
long as the program reports an error.
To modify a curve, simply select that curve, and the two axis edit fields will open revealing its
expression. You may edit freely.
If you have created a curve using the simpler method presented earlier, you can still use this
editing dialog. For example, let’s say you have chosen the z component of the body named
ball. If you select the curve from the list in the edit fields, you will find the following
expressions:
Horizontal axis
time
Vertical axis
ball.p[3]
Here the expression time is a variable that shows the actual simulation time. The ball.p[3]is
the z component ([3] = z) of the position ( .p ) the body ball (ball is the identifier). The
diagram gets a value at every time step, and adds a point on the plane and adds the point to the
curve.
5.5.4.1.2 Appearance page
The appearance of the diagram can be altered using tools on the appearance page. Let's go
through the possible settings.
On the Axis panel you can change the settings of the axis. If the Scrolling box is checked at
drawing time, the program will scroll the axis if necessary; i.e., if the maximum or minimum
value of the curve is bigger or smaller then the Upper or Lower limit. There are two ways to
treat this. The first is to 'change axis limits', which means that the limits will be pushed out.
The second way is to 'shift interval', which shifts the limits together.
Clicking on one of the two buttons–X-axis and Y-axis–will bring up another dialog. Another
way to reach this dialog is to move the mouse over the axis of the diagram drawn in the
description window and double click on it. The dialog contains the following:
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