Simulink.Parameter

Store, share, and configure parameter values

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Description

Create a Simulink.Parameter object to set the value of one or more block parameters in a model, such as the Gain parameter of a Gain block. You create the object in a workspace or in a data dictionary. Set the parameter value in the object, then reference the object from the block.

Use a Simulink.Parameter object to:

  • Share a value among multiple block parameters.

  • Represent an engineering constant or a tunable calibration parameter.

  • Separate a parameter value from its data type and other properties.

  • Configure parameter data for code generation.

The Value property of the object stores the parameter value. To use the object in a model, set the value of a block parameter to an expression that includes the name of the object. Omit the Value property from the expression. For more information, see Use Parameter Objects.

For more information about block parameters, see Set Block Parameter Values and How Generated Code Stores Internal Signal, State, and Parameter Data (Simulink Coder).

Creation

Create a Simulink.Parameter object:

Syntax

paramObj = Simulink.Parameter
paramObj = Simulink.Parameter(paramValue)

Description

paramObj = Simulink.Parameter returns a Simulink.Parameter object with default property values.

paramObj = Simulink.Parameter(paramValue) returns a Simulink.Parameter object and initializes the Value property to paramValue.

Properties

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For information about the properties in the property dialog box of a Simulink.Parameter object, see Simulink.Parameter Property Dialog Box.

Specifications for generating code for the parameter object, returned as a Simulink.CoderInfo object.

This property is read only. Instead, modify the properties of the Simulink.CoderInfo object that this property contains.

For example, the StorageClass property of the Simulink.CoderInfo object determines how Simulink® code generation toolboxes allocate memory for the parameter object in the generated code. For more information, see C Code Generation Configuration for Model Interface Elements (Simulink Coder) and Choose Storage Class for Controlling Data Representation in Generated Code (Embedded Coder).

Numeric complexity of the parameter value, returned as 'real' (if the value is real) or 'complex' (if the value is complex). Simulink determines the complexity from the parameter value that you specify in the Value property. This property is read only.

Data Types: char

Data type of the parameter value in the Value property, specified as 'auto' or a character vector. When you simulate the model or generate code, Simulink casts the value to the specified data type.

If you specify 'auto', the default setting, the parameter object uses the same data type as the block parameters that use the object. See Reduce Maintenance Effort with Data Type Inheritance.

When you set the Value property to something other than a double number, the object typically sets the DataType property based on the value of the Value property. For example, when you set the Value property to int8(5), the object sets the value of the DataType property to 'int8'.

To explicitly specify a built-in data type (see Data Types Supported by Simulink), specify one of these options:

  • 'double'

  • 'single'

  • 'half'

  • 'int8'

  • 'uint8'

  • 'int16'

  • 'uint16'

  • 'int32'

  • 'uint32'

  • 'int64'

  • 'uint64'

  • 'boolean'

To specify a fixed-point data type, use the fixdt function. For example, specify 'fixdt(1,16,5)'.

If you use a Simulink.AliasType or Simulink.NumericType object to create and share custom data types in your model, specify the name of the object.

To specify an enumerated data type, use the name of the type preceded by Enum:. For example, specify 'Enum: myEnumType'.

When you store a structure or array of structures in the Value property of the object, the object sets the DataType property to 'struct'. To specify a Simulink.Bus object as the data type, use the name of the bus object preceded by Bus:. For example, specify 'Bus: myBusObject'.

Example: 'auto'

Example: 'int8'

Example: 'fixdt(1,16,5)'

Example: 'myAliasTypeObject'

Example: 'Enum: myEnumType'

Example: 'Bus: myBusObject'

Data Types: char

Custom description of the parameter object, specified as a character vector. Use this property to document the significance that the parameter object has in your algorithm.

If you have an Embedded Coder® license, you can configure this description to appear in the generated code as a comment. See Simulink data object descriptions (Embedded Coder).

Example: 'This parameter represents the maximum rotation speed of the engine.'

Data Types: char

Dimensions of the value stored in the Value property, returned as a row vector or specified as a character vector.

When you set the Value property of the object, the object sets the value of the Dimensions property to a double row vector. The vector is the same vector that the size function returns.

To use symbolic dimensions, specify a character vector. See Implement Dimension Variants for Array Sizes in Generated Code (Embedded Coder).

Example: [1 3]

Example: '[1 myDimParam]'

Data Types: double | char

Maximum value that the Value property of the object can store, specified as a real double scalar.

The default value is empty, which means the parameter value does not have a maximum.

If you store a complex number in the Value property, the Max property applies separately to the real and imaginary parts.

If you store a structure in the Value property, the object ignores the Max property. Instead, use a Simulink.Bus object as the data type of the parameter object and specify a maximum value for each field by using the elements of the bus object. See Control Field Data Types and Characteristics by Creating Parameter Object.

If Value is greater than the maximum value or if the maximum value is outside the range of the object data type, Simulink generates a warning. When updating the diagram or starting a simulation, Simulink generates an error.

For more information about how Simulink uses this property, see Specify Minimum and Maximum Values for Block Parameters.

Example: 5.32

Data Types: double

Minimum value that the Value property of the object can store, specified as a real double scalar.

The default value is empty, which means the parameter value does not have a minimum.

If you store a complex number in the Value property, the Min property applies separately to the real and imaginary parts.

If you store a structure in the Value property, the object ignores the Min property. Instead, use a Simulink.Bus object as the data type of the parameter object and specify a minimum value for each field by using the elements of the bus object. See Control Field Data Types and Characteristics by Creating Parameter Object.

If Value is less than the minimum value or if the minimum value is outside the range of the object data type, Simulink generates a warning. When updating the diagram or starting a simulation, Simulink generates an error.

For more information about how Simulink uses this property, see Specify Minimum and Maximum Values for Block Parameters

Example: -0.92

Data Types: double

Physical unit of parameter value, specified as a character vector that describes a valid unit. For more information, see Unit Specification in Simulink Models.

Example: 'degC'

Data Types: char

Value to use in block parameters, specified as any of these valid values:

You can also use MATLAB® syntax to specify the value.

Example ExpressionDescription
15.23

Specifies a scalar value

[3 4; 9 8]

Specifies a matrix

3+2i

Specifies a complex value

struct('A',20,'B',5)

Specifies a structure with two fields, A and B, with double-precision values 20 and 5.

Organize block parameters into structures (see Organize Related Block Parameter Definitions in Structures) or initialize the signal elements in a bus (see Specify Initial Conditions for Bus Signals).

slexpr('myVar + myOtherVar')Specifies the expression myVar + myOtherVar where myVar and myOtherVar are other MATLAB variables or parameter objects. Simulink preserves this mathematical relationship between the object and the variables.

To use a Simulink.Parameter object to store a value of a particular numeric data type, specify the ideal value with the Value property and control the type with the DataType property.

If you set the Value property by using a typed expression such as single(32.5), the DataType property changes to reflect the new type. A best practice is to use an expression that is not typed to avoid accumulating numerical error through repeated quantizations or data type saturation, especially for fixed-point data types.

Example: 3.15

Example: 1.2 + 3.2i

Example: true

Example: myEnumType.myEnumValue

Example: struct('field1',15,'field2',7.32)

Example: slexpr('myVar + myOtherVar')

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | struct | fi | enum
Complex Number Support: Yes

Examples

Use Parameter Object to Set Value of Gain Parameter

  1. At the command prompt, create a Simulink.Parameter object.

    myParam = Simulink.Parameter;

  2. Assign a numeric value to the Value property.

    myParam.Value = 15.23;

  3. Specify the minimum and maximum values the parameter can take with the Min and Max properties.

    myParam.Min = 10.11;
myParam.Max = 25.27;

  4. Open a new Simulink model. Add a Gain block and set its Gain parameter to myParam. During simulation, the Gain parameter uses the value 15.23.

Change Value Stored by Parameter Object

  1. At the command prompt, create a Simulink.Parameter object that stores the value 2.52.

    myParam = Simulink.Parameter(2.52);

  2. Change the value by accessing the Value property of the object. This technique preserves the values of the other properties of the object.

    myParam.Value = 1.13;

Create Parameter Object with Specific Numeric Data Type

To reduce model maintenance, you can leave the DataType property at its default value, auto. The parameter object acquires a data type from the block parameter that uses the object.

To reduce the risk of the data type changing when you make changes to signal data types and other data types in your model, you can explicitly specify a data type for the parameter object. For example, when you generate code that exports parameter data to your custom code, explicitly specify a data type for the object.

  1. At the MATLAB command prompt, create a Simulink.Parameter object that stores the value 18.25.

    myParam = Simulink.Parameter(18.25);

    The expression 18.25 returns the number 18.25 with the double-precision, floating-point data type double. The Value property stores the number 18.25 with double precision.

  2. Use the DataType property to specify the single-precision data type single.

    myParam.DataType = 'single';

    When you simulate or generate code, the object casts the value of the Value property, 18.25, to the data type specified by the DataType property, single.

Set Parameter Value to a Mathematical Expression

This example shows how to set the value of a parameter object, myParam, to the sum of two other variables, myVar and myOtherVar. With this technique, when you change the values of the independent variables, Simulink immediately calculates the new value of the parameter object.

  1. Create the two independent variables.

    myVar = 5.2;
myOtherVar = 9.8;

  2. Create the parameter object.

    myParam = Simulink.Parameter;

  3. Set the value of the parameter object to the expression myVar + myOtherVar.

    myParam.Value = slexpr('myVar + myOtherVar')

    When you simulate or generate code, the expression evaluates to 15.

See Also

| | | | | (AUTOSAR Blockset)

Topics

Introduced before R2006a

Simulink Documentation

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