tril

Lower triangular part of matrix

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Syntax

L = tril(A)
L = tril(A,k)

Description

example

L = tril(A) returns the lower triangular portion of matrix A.

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

Examples

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Open Live Script

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

A = ones(4)
A = 4×4

     1     1     1     1
     1     1     1     1
     1     1     1     1
     1     1     1     1


B = tril(A)
B = 4×4

     1     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 = 4×4

     0     0     0     0
     1     0     0     0
     1     1     0     0
     1     1     1     0

Input Arguments

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Input matrix.

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

Diagonals to include, specified as a scalar. k = 0 is the main diagonal, k > 0 is above the main diagonal, and k < 0 is 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 blocks in this graphic depict the lower triangular portion of a 6-by-6 matrix.

Extended Capabilities

See Also

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Introduced before R2006a

MATLAB Documentation

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