Sigmoid Layer - Sigmoid layer - Simulink (original) (raw)
Sigmoid layer
Since R2024b
Libraries:
Deep Learning Toolbox / Deep Learning Layers / Activation Layers
Description
The Sigmoid Layer block applies a sigmoid function to layer input such that the output is bounded in the interval (0,1).
The exportNetworkToSimulink function generates this block to represent a sigmoidLayer object. Because it applies an element-wise operation, this block supports input data of any format and outputs data that has the same dimensions and format as the input.
Ports
Input
The matrix to which to apply the sigmoid function.
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point
Output
The result of applying the sigmoid function on the input matrix.
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point
Parameters
To edit block parameters interactively, use theProperty Inspector. From the Simulink® Toolstrip, on the Simulation tab, in thePrepare gallery, select Property Inspector.
Data Types
Specify the type of approximation for computing the output.
| Approximation Method | Data Types Supported | When to Use This Method |
|---|---|---|
| None (default) | Floating point | You are processing only floating point data. |
| CORDIC | Floating point (double and single) and fixed point with aBias value of 0 and aSlope value of a power of 2 | You are processing fixed point data and want to deploy to FPGA hardware. |
| Lookup | Floating point and fixed point | You are processing fixed point data and want to generate C/C++ code. |
For more information about the CORDIC approximation method, see cordictanh (Fixed-Point Designer).
Programmatic Use
| Block Parameter: ApproximationMethod | |
|---|---|
| Type: character vector | |
| Values: 'none' | 'CORDIC' | 'Lookup' |
| Default: 'none' |
Lower value of the output range that the software checks.
The software uses the minimum to perform:
- Parameter range checking (see Specify Minimum and Maximum Values for Block Parameters (Simulink)) for some blocks.
- Simulation range checking (see Specify Signal Ranges (Simulink) and Enable Simulation Range Checking (Simulink)).
- Automatic scaling of fixed-point data types.
- Optimization of the code that you generate from the model. This optimization can remove algorithmic code and affect the results of some simulation modes such as SIL or external mode. For more information, see Optimize using the specified minimum and maximum values (Embedded Coder).
Tips
Output minimum does not saturate or clip the actual output signal. Use the Saturation (Simulink) block instead.
Programmatic Use
To set the block parameter value programmatically, use the set_param (Simulink) function.
| Parameter: | OutMin |
|---|---|
| Values: | '[]' (default) | scalar in quotes |
Upper value of the output range that the software checks.
The software uses the maximum value to perform:
- Parameter range checking (see Specify Minimum and Maximum Values for Block Parameters (Simulink)) for some blocks.
- Simulation range checking (see Specify Signal Ranges (Simulink) and Enable Simulation Range Checking (Simulink)).
- Automatic scaling of fixed-point data types.
- Optimization of the code that you generate from the model. This optimization can remove algorithmic code and affect the results of some simulation modes such as SIL or external mode. For more information, see Optimize using the specified minimum and maximum values (Embedded Coder).
Tips
Output maximum does not saturate or clip the actual output signal. Use the Saturation (Simulink) block instead.
Programmatic Use
To set the block parameter value programmatically, use the set_param (Simulink) function.
| Parameter: | OutMax |
|---|---|
| Values: | '[]' (default) | scalar in quotes |
Choose the data type for the output. The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType. When you select Inherit: Inherit via internal rule, Simulink chooses a data type to balance numerical accuracy, performance, and generated code size, while taking into account the properties of the embedded target hardware.
Programmatic Use
To set the block parameter value programmatically, use the set_param (Simulink) function.
| Parameter: | OutDataTypeStr |
|---|---|
| Values: | 'Inherit: Inherit via internal rule' (default) | |
Select this parameter to prevent the fixed-point tools from overriding theOutput data type you specify on the block. For more information, see Use Lock Output Data Type Setting (Fixed-Point Designer).
Programmatic Use
To set the block parameter value programmatically, use the set_param (Simulink) function.
| Parameter: | LockScale |
|---|---|
| Values: | 'off' (default) | 'on' |
Specify the rounding mode for fixed-point operations. For more information, seeRounding Modes (Fixed-Point Designer).
Block parameters always round to the nearest representable value. To control the rounding of a block parameter, enter an expression using a MATLAB® rounding function into the mask field.
Programmatic Use
To set the block parameter value programmatically, use the set_param (Simulink) function.
| Parameter: | RndMeth | |||||
|---|---|---|---|---|---|---|
| Values: | 'Floor' (default) | 'Ceiling' | 'Convergent' | 'Nearest' | 'Round' | 'Simplest' | 'Zero' |
Specify whether overflows saturate or wrap.
on— Overflows saturate to either the minimum or maximum value that the data type can represent.off— Overflows wrap to the appropriate value that the data type can represent.
For example, the maximum value that the signed 8-bit integerint8 can represent is 127. Any block operation result greater than this maximum value causes overflow of the 8-bit integer.
- With this parameter selected, the block output saturates at 127. Similarly, the block output saturates at a minimum output value of -128.
- With this parameter cleared, the software interprets the overflow-causing value as
int8, which can produce an unintended result. For example, a block result of 130 (binary 1000 0010) expressed asint8is -126.
Tips
- Consider selecting this parameter when your model has a possible overflow and you want explicit saturation protection in the generated code.
- Consider clearing this parameter when you want to optimize efficiency of your generated code. Clearing this parameter also helps you to avoid overspecifying how a block handles out-of-range signals. For more information, see Troubleshoot Signal Range Errors (Simulink).
- When you select this parameter, saturation applies to every internal operation on the block, not just the output or result.
- In general, the code generation process can detect when overflow is not possible. In this case, the code generator does not produce saturation code.
Programmatic Use
To set the block parameter value programmatically, use the set_param (Simulink) function.
| Parameter: | SaturateOnIntegerOverflow |
|---|---|
| Values: | 'off' (default) | 'on' |
Execution
Specify the discrete interval between sample time hits or specify another type of sample time, such as continuous (0) or inherited (-1). For more options, see Types of Sample Time (Simulink).
By default, the block inherits its sample time based on the context of the block within the model.
Programmatic Use
To set the block parameter value programmatically, use the set_param (Simulink) function.
| Parameter: SampleTime |
|---|
| Data Types: char |
| Values: '-1' (default) | scalar |
Extended Capabilities
Version History
Introduced in R2024b
The Output data type value options are 'Inherit: Inherit via internal rule' and <data type expression>. Previously, the Output data type value options were 'Inherit: Inherit via internal rule','Inherit: Keep MSB', 'Inherit: Keep LSB', 'Inherit: Inherit via back propagation','Inherit: Same as first input', and <data type expression>.
Block parameters do not depend on the value of Approximation method. Previously, the value of Approximation method had to be 'None' to enable the other block parameters.