ones

Create array of all ones

Description

X = ones returns the scalar 1.

example

X = ones(n) returns an n-by-n matrix of ones.

example

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

example

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

example

X = ones(___,typename) also specifies the data type (class) of X for any of the previous syntaxes. For example, ones(5,'int8') returns a 5-by-5 matrix of 8-bit integers.

example

X = ones(___,'like',p) specifies that X has the same data type, sparsity, and complexity (real or complex) as the numeric variable p.

Examples

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Create a 4-by-4 array of ones.

X = ones(4)
X = 4×4

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

Create a 2-by-3-by-4 array of ones.

X = ones(2,3,4);

size(X)
ans = 1×3

     2     3     4

Define a 3-by-2 array A.

A = [1 4 ; 2 5 ; 3 6];

sz = size(A)
sz = 1×2

     3     2

Create an array of ones that is the same size as A

X = ones(sz)
X = 3×2

     1     1
     1     1
     1     1

Create a 1-by-3 vector of ones whose elements are 16-bit unsigned integers.

X = ones(1,3,'uint16'),
X = 1x3 uint16 row vector

   1   1   1

class(X)
ans = 
'uint16'

Create a scalar 1 that is not real valued, but instead is complex like an existing array.

Define a complex vector.

p = [1+2i 3i];

Create a scalar 1 that is complex like p.

X = ones('like',p)
X = 1.0000 + 0.0000i

Define a 2-by-3 array of 8-bit unsigned integers.

p = uint8([1 3 5 ; 2 4 6]);

Create an array of ones that is the same size and data type as p.

X = ones(size(p),'like',p),
X = 2x3 uint8 matrix

   1   1   1
   1   1   1

class(X)
ans = 
'uint8'

Input Arguments

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Size of square matrix, specified as an integer value, defines the output as a square, n-by-n matrix of ones.

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

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

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

Size of each dimension, specified as two or more integer values, defines X as a sz1-by...-by-szN array.

  • If the size of any dimension is 0, then X 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, X, does not include those dimensions.

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

Output size, specified as a row vector of integer values. Each element of this vector indicates the size of the corresponding dimension.

  • If the size of any dimension is 0, then X 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, X, does not include those dimensions.

Example: sz = [2,3,4] defines X as a 2-by-3-by-4 array.

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

Output class, specified as 'double', 'single', 'logical', 'int8', 'uint8', 'int16', 'uint16', 'int32', 'uint32', 'int64', or 'uint64'.

Prototype, specified as a variable.

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

Extended Capabilities

Introduced before R2006a