# Documentation

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# LDPC Encoder

Encode binary low-density parity-check code specified by parity-check matrix

## Library

Block sublibrary of Error Detection and Correction

## Description

This block supports encoding of low-density parity-check (LDPC) codes, which are linear error control codes with sparse parity-check matrices and long block lengths that can attain performance near the Shannon limit.

Both the input and the output are discrete-time signals. The ratio of the output sample time to the input sample time is $k/n$. The input must be a real $k×1$ column vector signal.

The output signal inherits the data type from the input signal, and the input must be binary-valued (0 or 1). For information about the data types each block port supports, see the Supported Data Type table on this page.

 Note:   Model initialization or update may take a long time, because a large matrix may need to be inverted (when the last (n – k) columns of the parity-check matrix is not triangular).

## Parameters

Parity-check matrix

This block can accept a sparse matrix with dimension n -k by n (where n >k > 0) of real numbers. All nonzero elements must be equal to 1. The upper bound limit for the value of n is 231-1

The default value is the parity-check matrix of the half-rate LDPC code from the DVB-S.2 standard.

## Supported Data Type

PortSupported Data Types
In
• Double-precision floating point

• Single-precision floating point

• Boolean

• 8-, 16-, and 32-bit signed integers

• 8-, 16-, and 32-bit unsigned integers

Out
• Double-precision floating point

• Single-precision floating point

• Boolean

• 8-, 16-, and 32-bit signed integers

• 8-, 16-, and 32-bit unsigned integers

## Examples

Enter `commdvbs2` at the command line to see an example that uses this block.