<abs>

Note

The <abs> element used inside the FlightGear <expression> tag is distinct from the <abs> element used in JSBSim for XML configuration files - although they are closely related and both perform the same mathematical operation.

Overview

The <abs> element takes the absolute value of a <property> child element. It is the same principle as functions of the same name in many programming languages.

Tip

For more information about absolute values in mathematics, see the Wikipedia article on the subject.

Syntax

The <abs> element must be a child element of an <expression> element, and the <abs> element

must have a <property> child element.

Example

One use case for the <abs> element is when a numerical value needs to be checked or used in a calculation, but whether or not the value is positive or negative is irrelevant.

In this example, passing the /velocities/vertical-speed-fps as a value to the <abs> element will return the vertical speed as a positive number, regardless of whether its value is positive or negative.

<abs>
    <property>/velocities/vertical-speed-fps</property>
</abs>