Complex to Magnitude-Angle

Compute magnitude and/or phase angle of complex signal

• 

Libraries:
Simulink / Math Operations

Description

The Complex to Magnitude-Angle block outputs the magnitude and/or phase angle of the input signal, depending on the setting of the Output parameter. The outputs are real values of the same data type as the block input. The input can be an array of complex signals, in which case the output signals are also arrays. The magnitude signal array contains the magnitudes of the corresponding complex input elements. The angle output similarly contains the angles of the input elements.

Ports

Input

Port_1 — Input signal

scalar | vector | matrix

Complex input signal that the block computes and outputs the magnitude and/or the phase angle.

Limitations

Fixed-point data types are supported only when you set the Approximation method to CORDIC.

Data Types: single | double

Output

Port_1 — Magnitude

scalar | vector | matrix

Output signal that is the magnitude and/or phase angle of the input signal. To choose the output, set the Output parameter.

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

Port_2 — Radian phase angle

scalar | vector | matrix

Radian phase angle, returned as a real-valued scalar, vector, or matrix.

Dependencies

• To enable this port, set Output to Magnitude and angle or Angle.

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

Parameters

Output — Magnitude and/or phase angle output specification

Magnitude and angle (default) | Magnitude | Angle

Specify if the output is the magnitude and/or the phase angle in radians of the input signal.

Programmatic Use

Parameter: Output

Type: character vector

Values: 'Magnitude and angle' | 'Magnitude' | 'Angle'

Default: 'Magnitude and angle'

Approximation method — Approximation method

None (default) | CORDIC

Specify the type of approximation for computing output.

Approximation Method	Data Types Supported	When to Use This Method
None (default)	Floating-point	You want to use the default Taylor series algorithm.
CORDIC	Floating-point and fixed-point	You want a fast, approximate calculation.

The block uses these data type propagation rules.

Data Type of Complex Input	Approximation Method	Data Type of Magnitude Output	Data Type of Angle Output
Floating point	None or CORDIC	Same as input	Same as input
Signed, fixed point	CORDIC	fixdt(1, WL + 2, FL) where: WL = input word length of the magnitude + 2 + 1 FL = input fraction length of the magnitude	fixdt(1, WL + 2, FL) where: WL = input word length of the magnitude -3, for best precision for [-pi, pi) FL = input fraction length of the angle
Unsigned, fixed point	CORDIC	fixdt(1, WL + 3, FL) where: WL = input word length of the magnitude + 2 FL = input fraction length of the magnitude	fixdt(1, WL + 3, FL) where: WL = input word length of the angle - 2, for best precision fraction length for range [0, pi/2] FL = input fraction length of the angle

Programmatic Use

Block Parameter: ApproximationMethod

Type: character vector

Values: 'None' | 'CORDIC'

Default: 'None'

Number of iterations — Number of iterations for CORDIC algorithm

11 (default) | positive integer, less than or equal to word length of fixed-point input

Number of iterations the CORDIC algorithm performs, specified as a positive integer-valued scalar. Increasing the number of iterations can produce more accurate results but also increases the expense of the computation and adds latency.

Data Type of Block Inputs	Value You Can Specify
Floating-point	A positive integer. The maximum value is 52 for double or 23 for single.
Fixed-point	A positive integer that does not exceed the word length of the magnitude input or the word length of the phase angle input, whichever value is smaller.

Dependencies

To enable this parameter, set Approximation method to CORDIC.

Programmatic Use

Block Parameter: NumberOfIterations

Type: character vector

Values: positive integer, less than or equal to word length of fixed-point input

Default: '11'

Sample time (-1 for inherited) — Interval between samples

-1 (default) | scalar | vector

Specify the time interval between samples. To inherit the sample time, set this parameter to -1. For more information, see Specify Sample Time.

Dependencies

This parameter is visible only if you set it to a value other than -1. To learn more, see Blocks for Which Sample Time Is Not Recommended.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter:	SampleTime
Values:	"-1" (default) | scalar or vector in quotes

Block Characteristics

Data Types	double | single
Direct Feedthrough	yes
Multidimensional Signals	yes
Variable-Size Signals	yes
Zero-Crossing Detection	no

More About

CORDIC

CORDIC is an acronym for COordinate Rotation DIgital Computer. The Givens rotation-based CORDIC algorithm is one of the most hardware-efficient algorithms available because it requires only iterative shift-add operations (see References). The CORDIC algorithm eliminates the need for explicit multipliers. Using CORDIC, you can calculate various functions such as sine, cosine, arc sine, arc cosine, arc tangent, and vector magnitude. You can also use this algorithm for divide, square root, hyperbolic, and logarithmic functions.

Increasing the number of CORDIC iterations can produce more accurate results, but doing so increases the expense of the computation and adds latency.

Extended Capabilities

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

Version History

Introduced before R2006a

R2024b: Complex to Magnitude-Angle block supports fixed-point inputs

Complex to Magnitude-Angle block now supports the CORDIC approximation method. This method allows fixed-point inputs at input Port_1. To select the CORDIC method, set the new Approximation method parameter to CORDIC.

When you select the CORDIC method, the block icon updates. The new parameter, Number of iterations, lets you define the number of iterations for the CORDIC algorithm.