randn
產(chǎn)生均值為0，方差 σ^2 = 1，標(biāo)準(zhǔn)差σ = 1的正態(tài)分布的隨機(jī)數(shù)或矩陣的函數(shù)。
用法：
Y = randn(n)
返回一個(gè)n*n的隨機(jī)項(xiàng)的矩陣。如果n不是個(gè)數(shù)量，將返回錯(cuò)誤信息。
Y = randn(m,n) 或 Y = randn([m n])
返回一個(gè)m*n的隨機(jī)項(xiàng)矩陣。
Y = randn(m,n,p,...) 或 Y = randn([m n p...])
產(chǎn)生隨機(jī)數(shù)組。
Y = randn(size(A))
返回一個(gè)和A有同樣維數(shù)大小的隨機(jī)數(shù)組。
randn
返回一個(gè)每次都變化的數(shù)量。
s = randn('state')
舉例
Example 1. R = randn(3,4) 將生成矩陣
R =
1.1650 0.3516 0.0591 0.8717
0.6268 -0.6965 1.7971 -1.4462
0.0751 1.6961 0.2641 -0.7012
For a histogram of the randn distribution, see hist.
Example 2. 產(chǎn)生一個(gè)隨機(jī)分布的指定均值和方差的矩陣：將randn產(chǎn)生的結(jié)果乘以標(biāo)準(zhǔn)差，然后加上期望均值即可。例如，產(chǎn)生均值為0.6，方差為0.1的一個(gè)5*5的隨機(jī)數(shù)方式如下：
x = .6 + sqrt(0.1) * randn(5)
x =
0.8713 0.4735 0.8114 0.0927 0.7672
0.9966 0.8182 0.9766 0.6814 0.6694
0.0960 0.8579 0.2197 0.2659 0.3085
0.1443 0.8251 0.5937 1.0475 -0.0864
0.7806 1.0080 0.5504 0.3454 0.5813
其他類似函數(shù)：rand, randperm, sprand, sprandn
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randn
Normally distributed random numbers and arrays
Syntax
Y = randn(n)
Y = randn(m,n)
Y = randn([m n])
Y = randn(m,n,p,...)
Y = randn([m n p...])
Y = randn(size(A))
randn
s = randn('state')
Description
The randn function generates arrays of random numbers whose elements are normally distributed with mean 0, variance σ^2 = 1 , and standard deviation σ = 1.
Y = randn(n) returns an n-by-n matrix of random entries. An error message appears if n is not a scalar. Y = randn(m,n) or Y = randn([m n]) returns an m-by-n matrix of random entries. Y = randn(m,n,p,...) or Y = randn([m n p...]) generates random arrays. Y = randn(size(A)) returns an array of random entries that is the same size as A. randn, by itself, returns a scalar whose value changes each time it's referenced. s = randn('state') returns a 2-element vector containing the current state of the normal generator. To change the state of the generator: randn('state',s)Resets the state to s. randn('state',0)Resets the generator to its initial state. randn('state',j)For integer j, resets the generator to its jth state. randn('state',sum(100*clock))Resets it to a different state each time.ExamplesExample 1. R = randn(3,4) may produce R =
1.1650 0.3516 0.0591 0.8717
0.6268 -0.6965 1.7971 -1.4462
0.0751 1.6961 0.2641 -0.7012
For a histogram of the randn distribution, see hist. Example 2. Generate a random distribution with a specific mean and variance . To do this, multiply the output of randn by the standard deviation , and then add the desired mean. For example, to generate a 5-by-5 array of random numbers with a mean of .6 that are distributed with a variance of 0.1 x = .6 + sqrt(0.1) * randn(5)
x =
0.8713 0.4735 0.8114 0.0927 0.7672
0.9966 0.8182 0.9766 0.6814 0.6694
0.0960 0.8579 0.2197 0.2659 0.3085
0.1443 0.8251 0.5937 1.0475 -0.0864
0.7806 1.0080 0.5504 0.3454 0.5813
See Also rand, randperm, sprand, sprandn |
