Gain (Using Simulink)

Multiply block input by a specified value.

Library

Math

Description

The Gain block generates its output by multiplying its input by a specified gain factor. You can enter the gain as a numeric value, or as a variable or expression in the Gain parameter field. The input and gain can be a scalar, vector, or matrix. The Multiplication parameter lets you specify whether to use element-by-element or matrix multiplication of the input by the gain.

The Gain block icon displays the value entered in the Gain parameter field if the block is large enough. If the gain is specified as a variable, the block displays the variable's name.

To modify the gain during a simulation using a slider control (see Slider Gain).

Data Type Support

The Gain block's support for data types depends on whether you select matrix or element-wise multiplication.

For matrix multiplication, the input and the gain must be a real or complex scalar, vector, or matrix value of type single or double.

For element-wise multiplication, a Gain block accepts a real- or complex-valued scalar, vector, or matrix input of any data type except boolean and outputs a signal of the same data type as its input. The elements of an input vector must be of the same type. A Gain block's Gain parameter can also be a real- or complex-valued scalar, vector, or matrix of any data type. A Gain block observes the following type rules:

If the input is real and the gain is complex, the output is complex.

If the gain parameter's data type differs from the input signal's data type and the input data type can represent the gain, Simulink converts the gain to the input type before computing the output. Otherwise, Simulink halts the simulation and signals an error. For example, if the input data type is uint8 and the gain is -1, an error results. If typecasting the gain parameter to the input data type results in a loss of precision, Simulink issues a warning and continues the simulation.

If the output data type is an integer type and the gain block's Saturate on integer overflow option is selected, the block saturates if the output exceeds the maximum value representable by the block's output data type. In other words, the block outputs one plus the maximum positive or minimum negative value representable by the output data type. For example, if the output type is int8, the actual output is 127 if the computed output is greater than 127 and -128 if the computed output is less than -128.

Parameters and Dialog Box

Multiplication: Specifies the type of operation used to multiply the input:

K.*u (element-wise multiplication)

K*u (matrix multiplication with the gain as the left operand)

u*K (matrix multiplication with the gain as the right operand)

Gain: The gain, specified as a scalar, vector, matrix, variable name, or expression. The default is 1. If not specified, the data type of the Gain parameter is double. If the Gain parameter value is too long to be displayed in the block and element-wise multiplication is selected, the string -K- is displayed.
Saturate on integer overflow: This option is enable only for element-wise multiplication. If selected, this option causes the output of the Gain block to saturate on integer overflow. In particular, if the output data type is an integer type, the block output is the maximum value representable by the output type or the computed output, whichever is smaller in the absolute sense. If the option is not selected, Simulink takes that action specified by the Data overflow event option on the Diagnostics page of the Simulation Parameters dialog box (see The Diagnostics Pane).

Characteristics

Direct Feedthrough
Yes

Sample Time
Inherited from driving block

Scalar Expansion
Of input and Gain parameter

States
0

Dimensionalized
Yes

Zero Crossing
No

Direct Feedthrough	Yes
Sample Time	Inherited from driving block
Scalar Expansion	Of input and Gain parameter
States	0
Dimensionalized	Yes
Zero Crossing	No

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