Sort

Sort input elements by value

• 

Libraries:
DSP System Toolbox / Statistics

Description

The Sort block ranks the values of the input elements along each channel (column) in an Ascending or a Descending order, based on the Sort order you specify. Complex inputs are sorted by their magnitude, which is the sum of the squares of the real and imaginary components of the input. You can choose the Sort algorithm to be either Quick sort or Insertion sort. The quick sort algorithm uses a recursive sort method and is faster at sorting more than 32 elements. The insertion sort algorithm uses a nonrecursive method and is faster at sorting fewer than 32 elements. When you generate code, use the insertion sort algorithm to avoid recursive function calls.

The Mode parameter specifies the block's mode of operation, which you can set to Value, Index, or Value and Index.

Examples

Sort Data into Ascending and Descending Orders

This example shows how to use the Sort block to sort the input data into ascending and descending orders. The Array Plot shows the sorted and the unsorted data.

Open the SortExample model. The input in the model is a sinusoidal signal. The data in this signal is sorted into ascending and descending orders by the two Sort blocks. The blocks use the Quick sort algorithm to sort the data. You can also specify the blocks to output the index of the sorted values by setting the Mode parameter to Index or Value and Index.

Run the model. View the unsorted data and compare it with the sorted data in the Array Plot window.

Ports

Input

Port_1 — Data input

vector | matrix

The block accepts real-valued or complex-valued multichannel inputs. The input data type must be double precision, single precision, integer, or fixed point, with power-of-two slope and zero bias.

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

Output

Val — Sorted data

vector | matrix

The block sorts the data along each channel and outputs the sorted data through this port. The size, data type, and complexity of the sorted data matches that of the input data. The block sorts complex inputs according to their magnitude.

Dependencies

To enable this port, set the Mode parameter to Value and index or Value.

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

Idx — Index of the sorted data

vector | matrix

The output at this port contains the indices of the sorted data.

Dependencies

To enable this port, set the Mode parameter to Value and index or Index.

Data Types: uint32

Parameters

Main Tab

Mode — Specify whether block returns values, indices, or both

Value and Index (default) | Value | Index

When the Mode parameter is set to:

• Value — The block sorts the elements in each channel of the M-by-N input matrix in an ascending or descending order, based on what you specify in the Sort order parameter. The output at each sample time, Val, is an M-by-N matrix that contains the sorted columns of the input.

  The block sorts complex inputs according to their magnitude.

• Index — The block sorts the elements in each channel of the M-by-N input matrix, and outputs the index array, I. Each element in I is an integer of type uint32 that indexes the sorted value in the corresponding column of the input.

• Value and index — The block outputs the sorted values of the input data, Val, and the corresponding indices in the index array, I.

Sort order — Order of sorting

Ascending (default) | Descending

Specify to sort the input data in either ascending or descending order.

Sort algorithm — Sort method

Quick sort (default) | Insertion sort

The quick sort algorithm uses a recursive sort method and is faster at sorting more than 32 elements. The insertion sort algorithm uses a nonrecursive method and is faster at sorting fewer than 32 elements. When you generate code, to avoid recursive function calls, use the insertion sort algorithm.

Data Types Tab

Note

To use these parameters, the data input must be complex and fixed point. For all other inputs, the parameters on the Data Types tab are ignored. Complex inputs are sorted by their magnitude, which is the sum of the squares of the real and imaginary components of the input. The results of the squares of the real and imaginary parts are stored in the Product output data type. The result of the sum of the squares is stored in the Accumulator data type. The parameters on the Data Types tab are ignored for all other inputs.

Rounding mode — Method of rounding operation

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

Specify the rounding mode for fixed-point operations. For more details, see rounding mode.

Saturate on integer overflow — Method of overflow action

off (default) | on

When you select this parameter, the block saturates the result of its fixed-point operation. When you clear this parameter, the block wraps the result of its fixed-point operation. For details on saturate and wrap, see overflow mode for fixed-point operations.

Product output — Product output data type

Inherit: Same as input (default) | fixdt([],16,0)

The squares of the real and imaginary parts of the complex input are stored in the Product output data type.

You can set this parameter to:

• Inherit: Same as input — The product output data type is the same as the input data type.

• fixdt([],16,0) — The product output data type is an autosigned, binary-point, scaled, fixed-point data type with a word length of 16 bits and a fraction length of 0.

Alternatively, you can set the Product output data type by using the Data Type Assistant. To use the assistant, click the Show data type assistant button.

For more information on the data type assistant, see Specify Data Types Using Data Type Assistant (Simulink).

Accumulator — Accumulator data type

Inherit: Same as product output (default) | Inherit: Same as input | fixdt([],16,0)

The result of the sum of the squares of the real and imaginary parts of the complex input are stored in the Accumulator data type.

You can set this parameter to:

• Inherit: Same as product output — The accumulator data type is the same as the product output data type.

• Inherit: Same as input — The accumulator data type is the same as the input data type.

• fixdt([],16,0) — The accumulator data type is an autosigned, binary-point, scaled, fixed-point data type with a word length of 16 bits and a fraction length of 0.

Alternatively, you can set the Accumulator data type by using the Data Type Assistant. To use the assistant, click the Show data type assistant button.

For more information on the data type assistant, see Specify Data Types Using Data Type Assistant (Simulink).

Lock data type settings against changes by the fixed-point tools — Prevent fixed-point tools from overriding data types

off (default) | on

Select this parameter to prevent the fixed-point tools from overriding the data types you specify on the block.

Block Characteristics

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

Algorithms

Sort

The block produces results identical to the MATLAB^® sort function.

The output of the block is equivalent to the following MATLAB code, when Sort order is set to:

• Ascending — [Val,I] = sort(u,'ascend')

• Descending — [Val,I] = sort(u,'descend')

where:

• u is the data input.

• Val is the sorted output.

• I is the index of the sorted output.

When the input is complex, the block sorts the data according to the magnitude. The block computes the magnitude by taking the sum of the squares of the real and imaginary components of the complex input. This is identical to calling the sort function as [Val,I] = sort(u,...,'ComparisonMethod','abs').

Extended Capabilities

C/C++ Code Generation

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

Generated code relies on the memcpy or memset function (string.h) under certain conditions.

Version History

Introduced before R2006a