ͳѧһԸΪʹͳѧԡͰ취Ϊͳѧһϲͨȴ֪˵ͳƺͳѧ⣬ΪЩͳƺͳѧ⡣
ٸ㼸ƪܶѧʽʾԭģ
Уͳģⷨͳ鷨ǰѸΪоֵģⷽǰ鷨ȡͳֵƶδ֪ļ㷽
ؿһּ㷽ԭͨȥ˽һϵͳõҪֵ
װף˵ľͳѧͳ⡣ʹõĶǵصصͳѧԺ䡰鷨ȡͳֵͨȥ˽һϵͳõҪֵȵȣװͳƺͳѧ⼰
һٶȣ
https://baike.baidu.com/item/%E8%92%99%E7%89%B9%E5%8D%A1%E7%BD%97%E6%B3%95/1225057
ؿҲͳģⷨͳ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
δ֤ƣԭġ
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
ؿһּ㷽ԭͨȥ˽һϵͳõҪֵ
dzǿ൱ʵ֡˵ļ㷽ʱΨһеķϸ40"ټƻ"Դڶijؿޣʡ
еļ
һǣؿԲʦСڲһеԲǵ֮Ǧ/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
ؿ֣һͶ㷨
ҲֵĶ֡ͼʾһf(x)ҪabĶ֣ʵ·ʱǿһȽľںĻϣΪAreaȻοͶ㣬ںf(x)·ĵΪɫΪɫȻͳɫռе㣨ɫ+ɫıΪrôͿԾݴ˹f(x)abĶΪArear
עؿ巨óֵһȷ֮һֵҵͶԽԽʱֵҲԽӽʵֵ
ؿ֣
صһؿ巨ֵĵڶַʱҲΪƽֵ
ȡһֲͬ{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˻ܼ.
άٿƶؿӢMonte 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, ǾƳһıȽϾȷĦֵ
ҿDzϤ? û, Ǵɵ˼ ֻǿͳѧеļ, Monte CarloǼеģ, ȥֵ.
Monte Carloֻ˼ͳ, ض㷨ϻвͬʽ.
ȻMonte Carloֵֻܹô, δֲ֪, δ֪ģͲ, ȵ, ںܶMonte CarloӰ, MCMC.
ſһſؿʷ:
2040ڷ롤ŵ˹˹ķ˹÷˹˹Ī˹ʵΪƻʱؿ巽Ϊķ徭ؿijǮؿԸΪķ
bg2015072601
ؿԴĦɸһɵؿޣóԶIJҵҶ֪, Ǯ, һûоȷ. , ֻҪǸ϶ͽ, , ľиȫʶ, ?
ģCSDN:
ѧ߶ܿؿ巽Լpythonʵ
https://blog.csdn.net/bitcarmanlee/article/details/82716641A
ٸ㼸ƪܶѧʽʾԭģ
Уͳģⷨͳ鷨ǰѸΪоֵģⷽǰ鷨ȡͳֵƶδ֪ļ㷽
ؿһּ㷽ԭͨȥ˽һϵͳõҪֵ
װף˵ľͳѧͳ⡣ʹõĶǵصصͳѧԺ䡰鷨ȡͳֵͨȥ˽һϵͳõҪֵȵȣװͳƺͳѧ⼰
һٶȣ
https://baike.baidu.com/item/%E8%92%99%E7%89%B9%E5%8D%A1%E7%BD%97%E6%B3%95/1225057
ؿҲͳģⷨͳ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
δ֤ƣԭġ
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
ؿһּ㷽ԭͨȥ˽һϵͳõҪֵ
dzǿ൱ʵ֡˵ļ㷽ʱΨһеķϸ40"ټƻ"Դڶijؿޣʡ
еļ
һǣؿԲʦСڲһеԲǵ֮Ǧ/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
ؿ֣һͶ㷨
ҲֵĶ֡ͼʾһf(x)ҪabĶ֣ʵ·ʱǿһȽľںĻϣΪAreaȻοͶ㣬ںf(x)·ĵΪɫΪɫȻͳɫռе㣨ɫ+ɫıΪrôͿԾݴ˹f(x)abĶΪArear
עؿ巨óֵһȷ֮һֵҵͶԽԽʱֵҲԽӽʵֵ
ؿ֣
صһؿ巨ֵĵڶַʱҲΪƽֵ
ȡһֲͬ{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˻ܼ.
άٿƶؿӢMonte 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, ǾƳһıȽϾȷĦֵ
ҿDzϤ? û, Ǵɵ˼ ֻǿͳѧеļ, Monte CarloǼеģ, ȥֵ.
Monte Carloֻ˼ͳ, ض㷨ϻвͬʽ.
ȻMonte Carloֵֻܹô, δֲ֪, δ֪ģͲ, ȵ, ںܶMonte CarloӰ, MCMC.
ſһſؿʷ:
2040ڷ롤ŵ˹˹ķ˹÷˹˹Ī˹ʵΪƻʱؿ巽Ϊķ徭ؿijǮؿԸΪķ
bg2015072601
ؿԴĦɸһɵؿޣóԶIJҵҶ֪, 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



