关于rand 与 randn

rand:0-1均匀分布.均值m=(a+b)/2; 方差=(b-a).^2/12;

 

randn:0均值,方差1.

 

 

只有当rand和randn生成较大的数据时,均值和方差才会成立.比如N>100

 

样例:

a = randn(10000,1);

mean(a(:)) = 0.0033

std(a(:)) = 1.0011

 

b = rand(10000,1);

mean(b(:)) = 0.5014

std(b(:)) =  0.2891

 

备注:sqrt(1/12) = sqrt((1-0)/12) = 0.2887