dsp.Maximum System object

Find maximum value of input or sequence of inputs

Description

The dsp.Maximum object finds the maximum values of an input or sequence of inputs.

Note

The Running mode in the dsp.Maximum System object™ will be removed in a future release. To compute the running maximum in MATLAB^®, use the dsp.MovingMaximum System object instead.

To compute the maximum value of an input or sequence of inputs:

1. Create the dsp.Maximum object and set its properties.

2. Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects? (MATLAB).

Creation

Syntax

max = dsp.Maximum

max = dsp.Maximum(Name,Value)

Description

max = dsp.Maximum returns an object, max, that computes the value and index of the maximum elements in an input or a sequence of inputs along the specified Dimension.

max = dsp.Maximum(Name,Value) returns a maximum-finding object, max, with each specified property set to the specified value.

Properties

Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects (MATLAB).

ValueOutputPort — Output maximum value

true (default) | false

Set this property to true in order to output the maximum of the input.

Dependencies

This property applies only when you set the RunningMaximum property to false.

RunningMaximum — Calculate over single input or multiple inputs

false | true

When you set this property to true, the object computes the maximum value over successive calls to the object algorithm. When you set this property to false, the object computes the maximum value over the current input.

IndexOutputPort — Output index of maximum value

true (default) | false

Set this property to true to output the index of the maximum value of the input.

Dependencies

This property applies only when you set the RunningMaximum property to false.

ResetInputPort — Additional input to enable resetting of running maximum

false (default) | true

Set this property to true to enable resetting the running maximum. When you set this property to true, you must specify a reset input to the object algorithm to reset the running maximum.

Dependencies

This property applies only when you set the RunningMaximum property to true.

ResetCondition — Condition that triggers resetting of running maximum

Non-zero (default) | Rising edge | Falling edge | Either edge

Specify the event that resets the running maximum as one of | Rising edge | Falling edge | Either edge | Non-zero |.

Dependencies

This property applies only when you set the ResetInputPort property to true.

IndexBase — Numbering base for index of maximum value

One (default) | Zero

Specify whether to start the index numbering from One or Zero when computing the index of the maximum value.

Dependencies

This property applies only when you set the IndexOutputPort property to true.

Dimension — Dimension to operate along

Column (default) | All | Row | Custom

Specify how the maximum calculation is performed over the data as one of | All | Row | Column | Custom |.

Dependencies

This property applies when you set the RunningMaximum property to false.

CustomDimension — Numerical dimension to calculate over

1 (default) | positive integer

Specify the integer dimension of the input signal over which the object finds the maximum. The custom dimension cannot exceed the number of dimensions in the input signal.

Dependencies

This property only applies when you set the Dimension property to Custom.

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

Fixed-Point Properties

RoundingMethod — Rounding method for fixed-point operations

Floor (default) | Ceiling | | Convergent | Nearest | Round | Simplest | Zero

Specify the rounding method as one of | Ceiling | Convergent | Floor | Nearest | Round | Simplest | Zero |.

OverflowAction — Action to take when integer input is out-of-range

Wrap (default) | Saturate

Specify the overflow action as one of | Wrap | Saturate |.

ProductDataType — Data type of product

Same as input (default) | Custom

Specify the product fixed-point data type as one of | Same as input | Custom |.

CustomProductDataType — Product word and fraction lengths

numerictype([],32,30) (default) | numerictype

Specify the product fixed-point type as a scaled numerictype object with a Signedness of Auto.

Dependencies

This property applies only when you set the ProductDataType property to Custom.

AccumulatorDataType — Data type of accumulator

Same as product (default) | Same as input | Custom

Specify the accumulator fixed-point data type as one of | Same as product | Same as input | Custom |.

CustomAccumulatorDataType — Accumulator word and fraction lengths

numerictype([],32,30) (default) | numerictype

Specify the accumulator fixed-point type as a scaled numerictype object with a Signedness of Auto.

Dependencies

This property applies only when you set the AccumulatorDataType property to Custom.

Usage

For versions earlier than R2016b, use the step function to run the System object algorithm. The arguments to step are the object you created, followed by the arguments shown in this section.

For example, y = step(obj,x) and y = obj(x) perform equivalent operations.

Syntax

[val,ind] = max(x)

val = max(x)

ind = max(x)

val = max(x,r)

Description

[val,ind] = max(x) returns the maximum value, val, and the index or position of the maximum value, ind, along the specified Dimension of x.

val = max(x) returns the maximum value, val, of the input x. When the RunningMaximum property is true, val corresponds to the maximum value over successive calls to the object algorithm.

ind = max(x) returns the zero- or one-based index ind of the maximum value. To enable this type of processing, set the IndexOutputPort property to true and the ValueOutputPort and RunningMaximum properties to false.

val = max(x,r) resets the state of max based on the value of reset signal, r, and the ResetCondition property. To enable this type of processing, set the RunningMaximum property to true and the ResetInputPort property to true.

Input Arguments

x — Data input

vector | matrix

Data input, specified as a vector or a matrix. If x is a matrix, each column is treated as an independent channel. The maximum is determined along each channel. The object also accepts variable-size inputs. Once the object is locked, you can change the size of each input channel.

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

r — Reset signal

scalar

Reset signal used to reset the running maximum, specified as a scalar value. The object resets the running maximum if the reset signal satisfies the ResetCondition.

Dependencies

To enable this signal, set the RunningMaximum property to true and the ResetInputPort property to true.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | logical

Output Arguments

val — Maximum value of the input

scalar | vector

Maximum value of the input, returned as a scalar or a vector. The object determines the maximum value of the input along each channel. If the input is a column vector, the output is a scalar. If the input is a multichannel signal, the output signal is 1-by-N vector, where N is the number of input channels.

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

ind — Index of maximum

scalar | vector

Indices of the maximum values of the input, returned as a scalar or a vector. The object determines the indices of the maximum values of the input along each channel. If the input is a column vector, the output is a scalar. If the input is a multichannel signal, the output signal is 1-by-N vector, where N is the number of input channels.

Data Types: double | uint32

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object named obj, use this syntax:

release(obj)

Common to All System Objects

step	Run System object algorithm
release	Release resources and allow changes to System object property values and input characteristics
reset	Reset internal states of System object

Examples

Compute the Maximum and Running Maximum of a Signal

Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent step syntax. For example, myObject(x) becomes step(myObject,x).

Find a maximum value and its index.

max1 = dsp.Maximum;
x = randn(100,1);
[y, I] = max1(x)

y = 3.5784

I = 9

Compute a running maximum.

 max2 = dsp.Maximum;
 max2.RunningMaximum = true;
 x = randn(100,1);
 z = max2(x);
 plot(z);

y(i) is the minimum of all values in the vector x(1:i).

Algorithms

This object implements the algorithm, inputs, and outputs described on the Maximum block reference page. The object properties correspond to the block parameters.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

See System Objects in MATLAB Code Generation (MATLAB Coder).

HDL Code Generation

Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

This object supports HDL code generation if you have the HDL Coder™ installed. HDL Coder provides additional configuration options that affect HDL implementation and synthesized logic.