兰德n

正态分布的随机数

全部收缩一世npage

句法

x = randn

x = randn（（n）

x = randn（（sz1，，，，。。。，，，，szN)

x = randn（sz）

x = randn（（___，打字））

x = randn（（___，“喜欢”，p）

x = randn（（s，，，，___）

Description

x = randnreturns a random scalar drawn from the standard normal distribution.

例子

x = randn（（n）returns ann-by-nmatrix of normally distributed random numbers.

例子

x = randn（（sz1，，，，。。。，，，，szN）returns ansz1-by-...-by-szN一系列随机数量sz1，，，，。。。，，，，szN指示每个维度的大小。例如，兰德（3,4)returns a 3-by-4 matrix.

例子

x = randn（（sz）returns an array of random numbers where size vectorszdefines尺寸（x）。例如，兰德（[3 4]）returns a 3-by-4 matrix.

例子

x = randn（（___，，，，typename）返回一系列随机数数据类型typename。这typename一世nput can be either"single"or"double"。You can use any of the input arguments in the previous syntaxes.

例子

x = randn（（___，“喜欢”，p）returns an array of random numbers likep; that is, of the same data type and complexity (real or complex) asp。您可以指定e一世thertypenameor“喜欢”，但不是两者。

x = randn（（s，，，，___）generates numbers from random number streams一世nstead of the default global stream. To create a stream, useRandStream。您可以指定sFollowed by any of the input argument combinations in previous syntaxes.

Examples

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Matrix of Random Numbers

Open Live Script

Generate a 5-by-5 matrix of normally distributed random numbers.

r =兰德（5)

r =5×50。5377 -1.3077 -1.3499 -0.2050 0.6715 1.8339 -0.4336 3.0349 -0.1241 -1.2075 -2.2588 0.3426 0.7254 1.4897 0.7172 0.8622 3.5784 -0.0631 1.4090 1.6302 0.3188 2.7694 0.7147 1.4172 0.4889

双变量正常随机数

Open Live Script

Generate values from a bivariate normal distribution with specified mean vector and covariance matrix.

mu = [1 2];Sigma = [1 0.5;0.5 2];r = chol（sigma）;z = repmat（Mu，10,1） + randn（10,2）*r

z=10×21。5377 0.4831 2.8339 6.9318 -1.2588 1.8302 1.8622 2.3477 1.3188 3.1049 -0.3077 1.0750 0.5664 1.6190 1.3426 4.1420 4.5784 5.6532 3.7694 5.2595

Reset Random Number Generator

Open Live Script

Save the current state of the random number generator and create a 1-by-5 vector of random numbers.

s=rng; r = randn(1,5)

r =1×50。5377 1.8339 -2.2588 0.8622 0.3188

Restore the state of the random number generator tos，然后创建一个随机数的新的1 x-5向量。值与以前相同。

rng(s); r1 = randn(1,5)

r1 =1×50。5377 1.8339 -2.2588 0.8622 0.3188

3-D Array of Random Numbers

Open Live Script

Create a 3-by-2-by-3 array of random numbers.

x = randn（[3,2,3]）

x = x（：，：，1）= 0.5377 0.8622 1.8339 0.3188 -2.2588 -1.3077 x（：，：，：，：，：，2）= -0.4336 2.7694 0.3426 -1.3499 -1.3499 3.5784 3.5784 3.0349 x（3.0349 x（：0.，3）x（:，：-0.1241 0.7147 1.4897

指定随机数的数据类型

Open Live Script

Create a 1-by-4 vector of random numbers whose elements are single precision.

r =兰德（1，，，，4，，，，"single"）

r =1X4s一世ngle row vector0。5377 1.8339 -2.2588 0.8622

class(r)

ans ='单'

Size Defined by Existing Array

Open Live Script

Create a matrix of normally distributed random numbers with the same size as an existing array.

A = [3 2; -2 1]; sz = size(A); X = randn(sz)

X=2×20。5377 -2.2588 1.8339 0.8622

It is a common pattern to combine the previous two lines of code into a single line.

x = randn（size（a））;

Size and Data Type Defined by Existing Array

Open Live Script

Create a 2-by-2 matrix of single-precision random numbers.

p=s一世ngle([3 2; -2 1]);

Create an array of random numbers that is the same size and data type asp。

x = randn（size（p），“喜欢”，，，，p）

X=2x2单基质0。5377 -2.2588 1.8339 0.8622

class(X)

ans ='单'

随机复数数

Open Live Script

Generate 10 random complex numbers from the standard complex normal distribution.

a =兰德（10，，，，1，，，，“喜欢”，1i）

a =10×1complex0.3802 + 1.2968i -1.5972 + 0.6096i 0.2254 - 0.9247i -0.3066 + 0.2423i 2.5303 + 1.9583i -0.9545 + 2.1460i 0.5129 - 0.0446i 0.5054 - 0.1449i -0.0878 + 1.0534i 0.9963 + 1.0021i

具有指定平均值和协方差的随机复数数字

Open Live Script

By default,兰德（n，“喜欢”，1i）generates random numbers from the standard complex normal distribution. The real and imaginary parts are independent normally distributed random variables with mean0and variance1/2。这covariance matrix is of the form[1/2 0;0 1/2]。

z=兰德（50000,1,“喜欢”，1i）;cov_z = cov（real（z），imag（z），1）

cov_z =2×20.4980 0.0007 0.0007 0.4957

要指定更一般的复杂正态分布，请定义平均值和协方差矩阵。例如，将平均值指定为 $μ = 1 + 2 一世$ and the covariance matrix as $σ = [[\begin{array}{c} σ_{XX} & σ_{Xy} \\ σ_{yx} & σ_{yy} \end{array} 这是给予的 = [[\begin{array}{c} 2 & - 2 \\ - 2 & 4 \end{array} 这是给予的$ 。

mu = 1 + 2i; sigma = [2 -2; -2 4];

转换先前生成的数据以遵循新定义的复杂正态分布。包括sqrt(2)当数据缩放时，因为原始分布中的真实和虚部的差异为1/2。

r = chol（sigma）;z_comp = [real(z) imag(z)]; z = repmat(mu,50000,1) + z_comp*sqrt(2)*R*[1; 1i]; z(1:10)

ans =10×1complex1。7604 + 3.8331i -2.1945 + 6.4138i 1.4508 - 0.3002i 0.3868 + 3.0977i 6.0606 + 0.8560i -0.9090 + 8.2011i 2.0259 + 0.8850i 2.0108 + 0.6993i 0.8244 + 4.2823i 2.9927 + 2.0115i

输入参数

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`n`-Size of square matrix
一世nteger value

方形矩阵的大小，指定为整数值。

如果n是0，然后X是一个空矩阵。
如果n是negative, then it is treated as0。

`sz1，，，，。。。，，，，szN`-每个维度的大小（作为单独的参数）
一世nteger values

Size of each dimension, specified as separate arguments of integer values.

如果任何维度的大小为0，然后X是an empty array.
如果任何维度的大小为negative, then it is treated as0。
Beyond the second dimension,兰德n忽略尾随的尺寸为1。兰德（3,1,1,1)produces a 3-by-1 vector of random numbers.

`sz`-Size of each dimension (as a row vector)
一世nteger values

每个维度的大小,指定为一个行向量of integer values. Each element of this vector indicates the size of the corresponding dimension:

如果任何维度的大小为0，然后X是an empty array.
如果任何维度的大小为negative, then it is treated as0。
Beyond the second dimension,兰德n忽略尾随的尺寸为1。兰德（[3 1 1 1]）produces a 3-by-1 vector of random numbers.

Example:sz=[[23 4]创建一个2 x-3 x-4阵列。

`typename`-数据类型（类）创建
`"double"`（（default) |`"single"`

数据类型（类）要创建，指定为"double"，，，，"single"，或其他提供的类的名称兰德nsupport.

Example:兰德（5，“单身”）

`p`-Prototype of array to create
numeric array

Prototype of array to create, specified as a numeric array.

Example:兰德（5,"like",p)

Data Types:s一世ngle|double
复杂的数字支持：万博1manbetxYes

`s`-随机数流
`RandStream`目的

随机数流，，，，specified as aRandStream目的。

Example:s=RandStream("dsfmt19937"); randn(s,[3 1])

Tips

由兰德n是determined by the internal settings of the uniform pseudorandom number generator that underlies兰德，，，，兰德一世，，，，and兰德n。You can control that shared random number generator usingrng。

Extended Capabilities

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

Usage notes and limitations:

数据类型（类）必须是内置的MATLAB^®numeric type. For other classes, the static兰德nmethod is not invoked. For example,兰德（sz，，，，'myclass')does not invokemyclass.randn(sz)。
Size arguments must have a fixed size.
看代码生成工具箱功能的可变大小限制（（MATLAB Coder)。
如果启用了外部呼叫，并且兰德n不是从内部调用parforloop, generated MEX files use the same random number state as MATLAB in serial code. Otherwise, the generated MEX code and standalone code maintain their own random number state that is initialized to the same state as MATLAB.

Thread-Based Environment
使用MATLAB®在后台运行代码`backgroundPool`or accelerate code with Parallel Computing Toolbox™`ThreadPool`。

此功能完全支持基于线程的环境。万博1manbetx有关更多信息，请参阅在基于线程的环境中运行MATLAB功能。

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

Usage notes and limitations:

这stream syntax兰德（s，，，，___）是not supported on a GPU.
您可以指定typename作为'gpuArray'。如果you specifytypename作为'gpuArray'，数组的默认基础类型为double。
创建具有基础类型的GPU数组datatype，将基础类型指定为其他参数typename。例如，x = randn（3，datatype，'gpuarray'）creates a 3-by-3 GPU array of random numbers with underlying typedatatype。
您可以指定the underlying typedatatype作为one of these options:
- '双倍的'
- 'single'
- “逻辑”
- 'int8'
- 'uint8'
- 'int16'
- 'uint16'
- 'int32'
- 'uint32'
- 'int64'
- 'uint64'
You can also specify the numeric variablep作为agpuArray。
如果you specifyp作为agpuArray，这underlying type of the returned array is the same asp。

有关更多信息，请参阅在GPU上运行MATLAB功能（（Parallel Computing Toolbox)。

分布式阵列
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

Usage notes and limitations:

这stream syntax兰德（s，，，，___）是not supported forcodistibedor分散式arrays.
您可以指定typename作为'codistributed'or'分散式'。如果you specifytypename作为'codistributed'or'分散式'，返回数组的默认基础类型为double。
To create a distributed or codistributed array with underlying typedatatype，将基础类型指定为其他参数typename。例如，x = randn（3，datatype，“分布式”）创建一个带有基础类型的随机数的3 x-3分布式矩阵datatype。
您可以指定the underlying typedatatype作为one of these options:
- '双倍的'
- 'single'
- “逻辑”
- 'int8'
- 'uint8'
- 'int16'
- 'uint16'
- 'int32'
- 'uint32'
- 'int64'
- 'uint64'
You can also specifyp作为acodistibedor分散式大批。
如果you specifyp作为acodistibedor分散式数组，返回数组的基础类型与p。
For additionalcodistibedsyntaxes, see兰德n（（codistibed）（（Parallel Computing Toolbox)。

有关更多信息，请参阅Run MATLAB Functions with Distributed Arrays（（Parallel Computing Toolbox)。

版本历史记录

Introduced before R2006a

eXpand all

R2022a: Match complexity with`“喜欢”`，，，，and use`“喜欢”`和`RandStream`目的

这“喜欢”输入支持真实万博1manbetx和复杂的原型阵列。例如：

r = randn（2,2，“喜欢”，1i）

r =0。3802 + 1.2968i 0.2254 - 0.9247i -1.5972 + 0.6096i -0.3066 + 0.2423i

所有语法都支持此功能。万博1manbetx另外，您现在可以使用“喜欢”和aRandStream对象作为第一个输入兰德n。

R2014a: Match data type of an existing variable with`'like'`

To generate random numbers with the same data type as an existing variable, use the syntax兰德（__，'like'，p）。例如：

A = single(pi); r = randn(4,4,'like',A); class(r)

ans =s一世ngle

通过A时，此功能不可用RandStream目的作为the first input to兰德n。

R2013b: Non-integer size inputs are not supported

Errors starting in R2013b

Specifying a dimension that is not an integer causes an error. UseFloorto convert non-integer size inputs to integers.

R2008b:`'种子'`，，，，`'state'`，，，，and`'twister'`一世nputs are not recommended

Not recommended starting in R2008b

这re are no plans to remove these inputs, which control the random number generator that underlies兰德，，，，兰德一世and兰德n。However, therng由于这些原因，建议使用功能：

这'种子'and'state'generators are flawed.
条款'种子'and'state'是发电机的误导名称。'种子'refers to the MATLAB v4 generator, not the seed initialization value.'state'refers to the v5 generators, not the internal state of the generator.
这sethree inputs unnecessarily use different generators for兰德and兰德n。

有关更新代码的信息，请参阅Replace Discouraged Syntaxes of rand and randn。

也可以看看

兰德一世|兰德|rng|RandStream|sp兰德|普兰德|兰德perm

兰德n

句法

Description

Examples

Matrix of Random Numbers

双变量正常随机数

Reset Random Number Generator

3-D Array of Random Numbers

指定随机数的数据类型

Size Defined by Existing Array

Size and Data Type Defined by Existing Array

随机复数数

具有指定平均值和协方差的随机复数数字

输入参数

`n`-Size of square matrix
一世nteger value

`sz1，，，，。。。，，，，szN`-每个维度的大小（作为单独的参数）
一世nteger values

`sz`-Size of each dimension (as a row vector)
一世nteger values

`typename`-数据类型（类）创建
`"double"`（（default) |`"single"`

`p`-Prototype of array to create
numeric array

`s`-随机数流
`RandStream`目的

更多关于

标准的真实和标准复杂正常分布

Tips

Extended Capabilities

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

Thread-Based Environment
使用MATLAB®在后台运行代码`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™.

分布式阵列
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

版本历史记录

R2022a: Match complexity with`“喜欢”`，，，，and use`“喜欢”`和`RandStream`目的

R2014a: Match data type of an existing variable with`'like'`

R2013b: Non-integer size inputs are not supported

R2008b:`'种子'`，，，，`'state'`，，，，and`'twister'`一世nputs are not recommended

也可以看看

话题

兰德n

句法

Description

Examples

Matrix of Random Numbers

双变量正常随机数

Reset Random Number Generator

3-D Array of Random Numbers

指定随机数的数据类型

Size Defined by Existing Array

Size and Data Type Defined by Existing Array

随机复数数

具有指定平均值和协方差的随机复数数字

输入参数

n-Size of square matrix一世nteger value

sz1，，，，。。。，，，，szN-每个维度的大小（作为单独的参数）一世nteger values

sz-Size of each dimension (as a row vector)一世nteger values

typename-数据类型（类）创建"double"（（default) |"single"

p-Prototype of array to createnumeric array

s-随机数流RandStream目的

更多关于

标准的真实和标准复杂正常分布

Tips

Extended Capabilities

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

Thread-Based Environment使用MATLAB®在后台运行代码backgroundPoolor accelerate code with Parallel Computing Toolbox™ThreadPool。

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

分布式阵列Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

版本历史记录

R2022a: Match complexity with“喜欢”，，，，and use“喜欢”和RandStream目的

R2014a: Match data type of an existing variable with'like'

R2013b: Non-integer size inputs are not supported

R2008b:'种子'，，，，'state'，，，，and'twister'一世nputs are not recommended

也可以看看

话题

`n`-Size of square matrix
一世nteger value

`sz1，，，，。。。，，，，szN`-每个维度的大小（作为单独的参数）
一世nteger values

`sz`-Size of each dimension (as a row vector)
一世nteger values

`typename`-数据类型（类）创建
`"double"`（（default) |`"single"`

`p`-Prototype of array to create
numeric array

`s`-随机数流
`RandStream`目的

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

Thread-Based Environment
使用MATLAB®在后台运行代码`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™.

分布式阵列
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

R2022a: Match complexity with`“喜欢”`，，，，and use`“喜欢”`和`RandStream`目的

R2014a: Match data type of an existing variable with`'like'`

R2008b:`'种子'`，，，，`'state'`，，，，and`'twister'`一世nputs are not recommended