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所跟帖: ÈüÀ¥ ÃÉÌØ¿¨ÂÞ·½·¨ºÍÖ÷ÒªÓ¦Óᣠ  2023-04-24 14:20:34  


作者: ÐìË®Á¼   ÕæÃ»Ïëµ½Äã»á´Àµ½ÕâÖ̶ֳȣ¬±ðÈËÃ÷Ã÷°×°×Ã÷ȷ˵ÊÇÂÛÊöͳ¼ÆÎÊÌâ 2023-04-24 17:47:47  [点击:1691]
ͳѧһԸΪʹͳѧԡͰ취Ϊͳѧһϲͨȴ֪˵ͳƺͳѧ⣬ΪЩͳƺͳѧ⡣

ٸ㼸ƪܶѧʽ޷ʾԭģ

Уͳģⷨͳ鷨ǰѸΪоֵģⷽǰ鷨ȡͳֵƶδ֪ļ㷽

ؿ޷һּ㷽ԭͨȥ˽һϵͳõҪֵ

װף˵ľͳѧͳ⡣ʹõĶǵصصͳѧԺ䡰鷨ȡͳֵͨȥ˽һϵͳõҪֵȵȣװ׾ͳƺͳѧ⼰


һٶȣ

https://baike.baidu.com/item/%E8%92%99%E7%89%B9%E5%8D%A1%E7%BD%97%E6%B3%95/1225057

ؿ޷Ҳͳģⷨͳ鷨ǰѸΪоֵģⷽǰ鷨ȡͳֵƶδ֪ļ㷽ؿĦɸijǣ÷Ϊıʶڶɢϵͳм顣ڼУͨһϵͳƵĸģּͣϽ飬ģϵͳԡ

MBAǿٿ
ؿ޷
https://wiki.mbalib.com/wiki/%E8%92%99%E7%89%B9%E5%8D%A1%E7%BD%97%E6%96%B9%E6%B3%95
δ֤޷ƣԭġ


һؿ壨Monte CarloӦ

ͼè.

2022-09-18 10:17:54 ޸

http://nooverfit.com/wp/%E7%94%A8%E4%BA%BA%E8%AF%9D%E8%A7%A3%E9%87%8A%E4%BB%80%E4%B9%88%E6%98%AF%E8%92%99%E7%89%B9%E5%8D%A1%E7%BD%97monte-carlo-method%E6%96%B9%E6%B3%95/

ר

ؿ޷һּ㷽ԭͨȥ˽һϵͳõҪֵ


dzǿ൱׶ʵ֡˵򵥵ļ㷽ʱΨһеķϸ40"ټƻ"Դڶijؿޣʡ

еļ
һǣؿ޷ԲʦСڲһеԲǵ֮Ǧ/4

ڣڲ10000㣨10000 (x, y)ĵľ룬ӶжǷԲڲ

ЩȷֲôԲڵĵӦռе /4˽ֵ4ǦеֵͨRԽűģ30000㣬еĹֵʵֵ0.07%

ʶͳѧҷLaw of the unconscious statistician
DZĺõһΪһԤ֪ʶһһάٿϸĽ͡
In probability theory and statistics, the law of the unconscious statistician (sometimes abbreviated LOTUS) is a theorem used to calculate the ֵ of a function g(X) of a X when one knows the probability distribution of X but one does not explicitly know the distribution of g(X). The form of the law can depend on the form in which one states the probability distribution of the X.

If it is a discrete distribution and one knows its PMF function ƒX (but not ƒg(X)), then the ֵ of g(X) is
E[g(X)]=xg(x)fX(x)
where the sum is over all possible values x of X.
If it is a continuous distribution and one knows its PDF function ƒX (but not ƒg(X)), then the ֵ of g(X) is
E[g(X)]=ҡ−g(x)fX(x)dx
LOTUSױһʲôأ˼ǣ֪Xĸʷֲ֪g(X)ķֲʱLOTUSʽܼg(X)ѧLOTUSĹʽ£

Xɢֲʱ
E[g(X)]=xg(x)fX(x)
Xֲʱ
E[g(X)]=ҡ−g(x)fX(x)dx
ʵڼʱ֪XPDFPMFδ֪g(X)PDFPMF

ؿ󶨻֣һͶ㷨
ҲֵĶ֡ͼʾһf(x)ҪabĶ֣ʵ·ʱǿһȽľںĻϣΪAreaȻοͶ㣬ںf(x)·ĵΪɫΪɫȻͳɫռе㣨ɫ+ɫıΪrôͿԾݴ˹f(x)abĶΪArear


עؿ巨óֵһȷ֮һֵҵͶԽԽʱֵҲԽӽʵֵ

ؿ󶨻֣
صһؿ巨󶨻ֵĵڶַʱҲΪƽֵ

ȡһ໥ֲͬ{Xi}Xi[a,b]ϷӷֲfXҲ˵fXXPDFPMFg∗(x)=g(x)fX(x)g∗(Xi)ҲһֲͬңΪg∗(x)ǹxĺԸLOTUSɵã

E[g∗(Xi)]=bag∗(x)fX(x)dx=bag(x)dx=I

ǿ

Pr(limN1Ni=1Ng∗(Xi)=I)=1

ѡ

I¯=1Ni=1Ng∗(Xi)

I¯1IƽֵI¯ΪIĽֵ

ҪĻʽ

I=bag(x)dx
бg(x)[a,b]ڿɻѡһм취ԽгĸܶȺfX(x)ʹ

g(x)0ʱfX(x)0axb
bafX(x)dx=1


g∗(x)=⎧⎩⎨⎪⎪g(x)fX(x),0,fX(x)0fX(x)=0

ôԭʽд

I=bag∗(x)fX(x)dx

ֵIJǣ

ӷֲfXXi (i=1,2,⋯,N)
ֵ
I¯=1Ni=1Ng∗(Xi)
ΪIĽֵII¯
a,bΪֵôfXȡΪȷֲ

fX(x)=⎧⎩⎨1b−a,0,axbotherwise

ʱԭĻʽΪ

I=(b−a)bag(x)1b−adx

岽£

[a,b]ϵľȷֲXi (i=1,2,⋯,N);
ֵ
I¯=b−aNi=1Ng(Xi)
ΪIĽֵII¯
ƽֱֵ۽
Բοס1һӡעֵļ[a,b]·


[a,b]֮ȡһxʱӦĺֵf(x)Ȼf(x)(b−a)Թ·Ҳǻ֣ȻֹƣƣǷdzԵġ


뵽[a,b]֮ȡһϵеxiʱxiȷֲȻѹȡƽΪֹƵһõĽֵIJԽԽ࣬ôֵĹҲԽԽӽ


˼·ǵõֹʽΪ

I¯=(b−a)1Ni=0N−1f(Xi)=1Ni=0N−1f(Xi)1b−a

עе1b−aǾȷֲPMF֮ǰƵؿֹʽһµġ



ȨΪCSDNͼè.ԭ£ѭCC 4.0 BY-SAȨЭ飬ת븽ԭijӼ
ԭӣhttps://blog.csdn.net/qq_39521554/article/details/79046646

David 9IJ

ӽʲôؿ(Monte Carlo Method)

Ǿڸ㷨пؿޡ(Monte Carlo), MCMC(Markov Chain Monte Carlo) , AlphaGoʹõؿ. ʵ, ؿޡһض㷨, һ˼߷ͳ. , ʵ˻ܼ򵥽.

άٿƶؿ޷ӢMonte Carlo methodĽ:

ʮʮڿѧķչ͵ӼķһԸͳΪָһdzҪֵ㷽ָʹαܶķ

Ӧȷ㷨

˵, ؿֵ, ǾȷĶһ, ǿԽܵĴΧ.

άٿһֱ۵:

330px-pi_30k

ʹؿ巽ֵ. 30000,еĹֵʵֵ0.07%.

ͼʵܼ, һ, һƽͶ30000, Dz֪ԲʦеֵǶ, ֪1/4Բ, ǰѺɫϵĵm, ɫϵĵn, ԼԲʦеĹϵ, дһԼڵʽ:

4m/(n+m)

m+nͶ, ֵļҲԽԽȷ, Ǿ͹ƳһıȽϾȷĦֵ

ҿDzϤ? û, Ǵɵ˼ ֻǿͳѧеļ޺, Monte CarloǼеģ, ȥֵ.

Monte Carloֻ˼ͳ, ض㷨ϻвͬʽ.

ȻMonte Carloֵֻܹô, δֲ֪, δ֪ģͲ, ȵ, ںܶMonte CarloӰ, MCMC.

ſһſؿ޷ʷ:

2040ڷ롤ŵ˹˹ķ˹÷޲˹˹Ī˹ʵΪƻʱؿ巽Ϊķ徭ؿijǮؿ޷ԸΪķ

bg2015072601

ؿ޷ԴĦɸһɵؿޣóԶIJҵҶ֪, Ǯ, һûоȷ. , ֻҪǸ϶ͽ, , ľиȫʶ, ?

ģCSDN:

ѧ߶ܿؿ巽Լpythonʵ

https://blog.csdn.net/bitcarmanlee/article/details/82716641A
���༭ʱ��: 2023-04-24 17:51:18

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