我想开发一个范围为 [0.42,1.19] 的对数正态分布,它的少数元素给出为D=[1.19,1.00,0.84,0.71,0.59,0.50,0.42]
. 平均值0.84
和标准差应尽可能小。还给出了 90% 的 cdf(= 90% 的晶粒)介于0.59 and 1.19
.
一旦我知道了包含给定条件的对数正态分布的所有元素,我就可以找到它的 pdf,这就是我所需要的。以下是我尝试过的简单步骤:
D=[1.19,1.00,0.84,0.71,0.59,0.50,0.42];
s=0.30; % std dev of the lognormal distribution
m=0.84; % mean of the lognormal distribution
mu=log(m^2/sqrt(s^2+m^2)); % mean of the associated normal dist.
sigma=sqrt(log((s^2/m^2)+1)); % std dev of the associated normal dist.
[r,c]=size(D);
for i=1:c
D_normal(i)=mu+(sigma.*randn(1));
w(i)=(D_normal(i)-mu)/sigma; % the probability or the wt. percentage
end
sizes=exp(D_normal);