tril

Lower triangular part of matrix

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Syntax

L = tril(A)

L =下三角阵(k)

Description

example

L = tril(A)returns thelower triangularportion of matrixA.

L = tril(A,k)returns the elements on and below the kth diagonal ofA.

Examples

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Extract Lower Triangular Portions of Matrix

Open Live Script

Create a 4-by-4 matrix of ones. Extract the lower triangular portion.

A = ones(4)

A =4×41 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

B = tril(A)

B =4×41 0 0 0 1 1 0 0 1 1 1 0 1 1 1 1

Extract only the elements below the main diagonal.

C = tril(A,-1)

C =4×40 0 0 0 1 0 0 0 1 1 0 0 1 1 1 0

Input Arguments

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`A`—Input matrix
matrix

Input matrix.

`k`—Diagonals to include
`0`(default) |scalar

Diagonals to include, specified as a scalar.k = 0is the main diagonal,k > 0is above the main diagonal, andk < 0is below the main diagonal.

Matrix with the main diagonal labeled as k=0. Values of k greater than zero are for diagonals above the main diagonal, and values of k less than zero are for diagonals below the main diagonal.

Example:tril(A,3)

More About

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Lower Triangular

The lower triangular portion of a matrix includes the main diagonal and all elements below it. The shaded elements in this graphic depict the lower triangular portion of a 6-by-6 matrix.

Extended Capabilities

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

Usage notes and limitations:

If you supply the argument that represents the order of the diagonal matrix, then it must be a real and scalar integer value.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Usage notes and limitations:

If you supply the argument that represents the order of the diagonal matrix, then it must be a real and scalar integer value.

Thread-Based Environment
Run code in the background using MATLAB®`backgroundPool`or accelerate code with Parallel Computing Toolbox™`ThreadPool`.

This function fully supports thread-based environments. For more information, seeRun MATLAB Functions in Thread-Based Environment.

GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

This function fully supports GPU arrays. For more information, seeRun MATLAB Functions on a GPU(Parallel Computing Toolbox).

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, seeRun MATLAB Functions with Distributed Arrays(Parallel Computing Toolbox).

已经rsion History

Introduced before R2006a

tril

Syntax

Description

Examples

Extract Lower Triangular Portions of Matrix

Input Arguments

A—Input matrixmatrix

k—Diagonals to include0(default) |scalar

More About

Lower Triangular

Extended Capabilities

C/C++ Code GenerationGenerate C and C++ code using MATLAB® Coder™.

GPU Code GenerationGenerate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Thread-Based EnvironmentRun code in the background using MATLAB®backgroundPoolor accelerate code with Parallel Computing Toolbox™ThreadPool.

GPU ArraysAccelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

Distributed ArraysPartition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

已经rsion History

See Also

`A`—Input matrix
matrix

`k`—Diagonals to include
`0`(default) |scalar

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

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Thread-Based Environment
Run code in the background using MATLAB®`backgroundPool`or accelerate code with Parallel Computing Toolbox™`ThreadPool`.

GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.