Simulink Reference

Abs

Output the absolute value of the input

Library

Simulink Math Operations and Fixed-Point Blockset Math

Description

The Abs block outputs the absolute value of the input.

For signed data types, the absolute value of the most negative value is problematic since it is not representable by the data type. In this case, the behavior of the block is controlled by the Saturate on integer overflow check box. If checked, the absolute value of the data type saturates to the most positive representable value. If not checked, the absolute value of the most negative value represented by the data type has no effect.

For example, suppose the block input is an 8-bit signed integer. The range of this data type is from -128 to 127, and the absolute value of -128 is not representable. If the Saturate on integer overflow check box is selected, then the absolute value of -128 is 127. If it is not selected, then the absolute value of -128 remains at -128.

Data Type Support

An Abs block accepts real signals of any data type supported by Simulink except boolean, including fixed-point data types. The Abs block also accepts complex single and double inputs. The block outputs a real value of the same data type as the input.

For a discussion on the data types supported by Simulink, refer to Data Types Supported by Simulink in the Using Simulink documentation.

Dialog Box

Saturate on integer overflow

When selected, the block maps signed integer input elements corresponding to the most negative value of that data type to the most positive value of that data type:

• For 8-bit integers, -128 is mapped to 127.
• For 16-bit integers, -32768 maps to 32767.
• For 32-bit integers, -2147483648 maps to 2147483647.

• When not selected, the block does not act on signed integer input elements corresponding to the most negative value of that data type.

• For 8-bit integers, -128 remains -128.
• For 16-bit integers, -32768 remains -32768.
• For 32-bit integers, -2147483648 remains -2147483648.

Enable zero crossing detection

Select to enable zero crossing detection. For more information, see Zero Crossing Detection in the Using Simulink documentation.

Characteristics

Dimensionalized	Yes
Direct Feedthrough	Yes
Sample Time	Inherited from driving block
Zero Crossing	No, unless Enable zero crossing detection is selected

Simulink Blocks

Action Port