Identity Matrix

Generate matrix with ones on main diagonal and ground values elsewhere

Since R2021b

• 

Libraries:
Simulink / Matrix Operations

Description

The Identity Matrix block outputs an identity matrix, similar to the MATLAB^® eye function. The block generates a square or rectangular matrix with ones on the main diagonal and zeros elsewhere.

Examples

Generate Unit-Diagonal and Identity Matrices

This example shows how to generate a 3-by-6 unit-diagonal matrix and a 5-by-5 identity matrix using the Identity Matrix block.

Ports

Input

Port_1 — Input signal

scalar | vector | matrix

Input signal used to determine dimensions of the output matrix, specified as a scalar, vector, or matrix. When the input signal is an M-by-N matrix, the block generates an M-by-N matrix output with the same sample period as the input. The values in the input matrix are ignored.

Dependencies

To enable this port, select the Inherit output port attributes from input port check box.

Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point

Output

Port_1 — Identity matrix

scalar | vector | matrix

Identity matrix, specified as a scalar, vector, or matrix.

Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point

Parameters

Inherit output port attributes from input port — Option for output port to inherit attributes from input port

off (default) | on

Select this check box for the output port to inherit its dimensions, sample period, and data type from the input port. Otherwise, clear this check box.

Programmatic Use

Block Parameter: InheritOutputPortAttributes

Type: character vector

Values: 'on' | 'off'

Default: 'off'

Output dimensions — Size of output matrix

5 (default) | scalar | two-element vector

The number of rows and columns in the output matrix. You can specify:

• A positive integer scalar M to create a square M-by-M output.

• A vector of positive integers, [M N], to create an M-by-N output.

Dependencies

To enable this parameter, clear the Inherit output port attributes from input port check box.

Programmatic Use

Block Parameter: OutputDimensions

Type: character vector

Values: scalar | two-element vector

Default: '5'

Output data type — Output data type

double (default) | single | int8 | uint8 | int16 | uint16 | int32 | uint32 | int64 | uint64 | boolean | fixdt(1,16,0) | Inherit: Inherit via back propagation | <data type expression>

Specify the output data type for this block. You can select one of these options:

• A rule that inherits a data type, for example, Inherit: Inherit via back propagation. When you select this option, the output data type and scaling matches that of the next downstream block.

• A built-in data type, such as double.

• An expression that evaluates to a valid data type, for example, fixdt(1,16).

For help setting data type parameters, display the Data Type Assistant by clicking the Show data type assistant button .

See Control Data Types of Signals for more information.

Programmatic Use

Block Parameter: OutDataTypeStr

Type: character vector

Values: 'Inherit: Inherit via back propagation' | 'double' | 'single' | 'half' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | | 'fixdt(1,16,0)' | '<data type expression>'

Default: 'double'

Mode — Data type mode

Inherit (default) | Built in | Fixed point | Expression

Select how you would like to specify the data type properties of the Output data type. You can choose:

• Inherit — Specify a rule for inheriting a data type, for example, Inherit: Same as input.

• Built in— Specify a built-in data type, for example, double.

• Fixed point — Specify the fixed-point attributes of the data type.

• Expression — Specify an expression that evaluates to a valid data type, for example, fixdt(1,16).

For more information, see Specify Data Types Using Data Type Assistant.

Signedness — Signedness of fixed-point data

Signed (default) | Unsigned

Specify whether the fixed-point data is signed or unsigned. Signed data can represent positive and negative values, but Unsigned data represents positive values only. For more information, see Specify Data Types Using Data Type Assistant.

Scaling — Method for scaling fixed-point data

Best precision (default) | Binary point

Specify the method for scaling your fixed-point data to avoid overflow conditions and minimize quantization errors. For more information, see Specify Data Types Using Data Type Assistant.

Dependencies

To enable this parameter, set Mode to Fixed point

Word length — Bit size of word that holds quantized integer

16 (default) | integer from 2 to 65,535

Specify the bit size of the word that holds the quantized integer as a positive integer from 2 to 65,535. For more information, see Specify Data Types Using Data Type Assistant.

Dependencies

To enable this parameter, set Mode to Fixed point.

Fraction length — Fraction length for fixed-point data type

0 (default) | integer scalar

Specify the fraction length of the fixed-point data type as a positive or negative integer scalar.

Dependencies

To enable this parameter, set Mode to Fixed point and Scaling to Binary point.

Data type override — Data type override mode

Inherit (default) | Off

Select the data type override mode for this signal. You can select:

• Inherit — Inherits the data type override setting specified for the model.

• Off — Ignores the data type override setting specified for the model and uses the fixed-point data type you specify.

Dependencies

To enable this parameter, set Mode to Built in or Fixed point. For more information, see Specify Data Types Using Data Type Assistant.

Sample time — Output sample period

1 (default) | scalar

The discrete sample period of the output, specified as a real-valued scalar.

Dependencies

To enable this parameter, clear the Inherit output port attributes from input port check box.

Programmatic Use

Block Parameter: SampleTime

Type: character vector

Values: scalar or vector

Default: '1'

Block Characteristics

Data Types	Boolean | double | fixed point | half | integer | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2021b

R2022a: Identity Matrix Block Added to Simulink Matrix Operations Library

The Identity Matrix block has been removed from the DSP System Toolbox > Math Functions > Matrices and Linear > Matrix Operations library. For equivalent functionality, use the Identity Matrix block in the Simulink > Matrix Operations library. All existing models continue to work.