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true

Logical 1 (true)

Syntax

Description

example

true is shorthand for the logical value 1.

example

T = true(n) is an n-by-n matrix of logical ones.

example

T = true(sz) is an array of logical ones where the size vector, sz, defines size(T). For example, true([2 3]) returns a 2-by-3 array of logical ones.

example

T = true(sz1,...,szN) is a sz1-by-...-by-szN array of logical ones where sz1,...,szN indicates the size of each dimension. For example, true(2,3) returns a 2-by-3 array of logical ones.

example

T = true(___,'like',p) returns an array of logical ones of the same sparsity as the logical variable p using any of the previous size syntaxes.

Examples

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Use true to generate a 3-by-3 square matrix of logical ones.

A = true(3)
class(A)
A =

  3×3 logical array

   1   1   1
   1   1   1
   1   1   1


ans =

logical

The result is of class logical.

Use true to generate a 3-by-2-by-2 matrix of logical ones.

true(3,2,2)
  3×2×2 logical array

ans(:,:,1) =

   1   1
   1   1
   1   1


ans(:,:,2) =

   1   1
   1   1
   1   1

Alternatively, you can use a size vector to specify the size of the matrix.

true([3,2,2])
  3×2×2 logical array

ans(:,:,1) =

   1   1
   1   1
   1   1


ans(:,:,2) =

   1   1
   1   1
   1   1

Note that specifying multiple vector inputs returns an error.

true along with false can be used to execute logic statements.

Test the logical statement

  ~(A and B) = (~A) or (~B)

for A = true and B = false.

~(true & false) == (~true) | (~false)
ans =

  logical

   1

The result is logical 1 (true), since the logical statements on both sides of the equation are equivalent. This logical statement is an instance of De Morgan's Law.

Generate a logical array of the same sparsity as the selected array.

A = logical(sparse(5,3));
whos A
  Name      Size            Bytes  Class      Attributes

  A         5x3                41  logical    sparse    

T = true(4,'like',A);
whos T
  Name      Size            Bytes  Class      Attributes

  T         4x4               184  logical    sparse    

The output array T has the same sparse attribute and data-type as the specified array A.

Input Arguments

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Size of square matrix, specified as an integer. n sets the output array size to n-by-n. For example, true(3) returns a 3-by-3 array of logical ones.

  • If n is 0, then T is an empty matrix.

  • If n is negative, then it is treated as 0.

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

Size vector, specified as a row vector of integers. For example, true([2 3]) returns a 2-by-3 array of logical ones.

  • If the size of any dimension is 0, then T is an empty array.

  • If the size of any dimension is negative, then it is treated as 0.

  • If any trailing dimensions greater than 2 have a size of 1, then the output, T, does not include those dimensions.

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

Size inputs, specified by a comma-separated list of integers. For example, true(2,3) returns a 2-by-3 array of logical ones.

  • If the size of any dimension is 0, then T is an empty array.

  • If the size of any dimension is negative, then it is treated as 0.

  • If any trailing dimensions greater than 2 have a size of 1, then the output, T, does not include those dimensions.

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

Prototype, specified as a logical variable.

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

Output Arguments

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Output of logical ones, returned as a scalar, vector, matrix, or N-D array.

Data Types: logical

More About

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Tips

  • true(n) is much faster and more memory efficient than logical(true(n)).

See Also

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Introduced before R2006a

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