连续性分布
[ + ] 均匀分布
记做 r,vX∼U(a,b)r,v X\sim U(a,b)r,vX∼U(a,b)
概率密度为:
f(x)={1b−a,a≤x≤b0,其他f(x) = \left \{ \begin{aligned} \frac{1}{b-a}&,a\leq x \leq b \\ 0&,其他 \end{aligned} \right. f(x)=⎩⎨⎧b−a10,a≤x≤b,其他
分布函数为:
F(x)={0,x<ax−ab−a,a≤x<b1,x≥bF(x) = \left \{ \begin{aligned} &0, &x<a\\ &\frac{x-a}{b-a},&a\le x < b\\ &1,&x\ge b \end{aligned} \right. F(x)=⎩⎪⎪⎪⎨⎪⎪⎪⎧0,b−ax−a,1,x<aa≤x<bx≥b
[ + ] 指数分布
密度函数为:
f(x)={λe−λx,x>00,x≤0
f(x) = \left\{
\begin{aligned}
&\lambda e^{-\lambda x},&x>0\\
&0,&x \le 0\\
\end{aligned}
\right.
f(x)={λe−λx,0,x>0x≤0
分布函数为:
F(x)={0,x<01−e−λx,x≤0F(x) = \left\{
\begin{aligned}
&0,&x<0\\
&1-e^{-\lambda x},&x\le 0
\end{aligned}
\right.
F(x)={0,1−e−λx,x<0x≤0
[ + ] 正态分布
传说中的咸鱼分布
概率密度为:
f(x)={λe−λx,x>00,x≤0f(x) = \left\{
\begin{aligned}
&\lambda e^{-\lambda x},&x>0\\
&0,&x \le 0
\end{aligned}
\right.f(x)={λe−λx,0,x>0x≤0
记做Exp(λ)Exp(\lambda)Exp(λ)