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+.. _arduino-abs:
+
+abs(x)
+======
+
+Description
+-----------
+
+(Macro) computes the absolute value of a number.
+
+Parameters
+----------
+
+**x**: the number
+
+Returns
+-------
+
+**x**: if **x** is greater than or equal to 0.
+
+**-x**: if **x** is less than 0.
+
+Warning
+-------
+
+Because of the way ``abs()`` is implemented, avoid using other
+functions or causing side effects inside the brackets, as it may lead
+to incorrect results ::
+
+    abs(a++);   // avoid this - yields incorrect results
+    
+    a++;          // use this instead -
+    abs(a);       // keep other math outside the function