argument of the maximum/minimum
argmaxf(x ) : ) x )取最大值时，x取的值
argminf(x ):f ) x取最小值时，x取的值
表示将目标函数设为最小值时的变量值
来自维基百科
In mathematics，argmax(orargmax ) standsfortheargumentofthemaximum，that is to say，thesetofpointsofthegivenargumentforwhichtion
在Words上，
isthesetofvaluesofxforwhichf(x ) has the largest value M. For example，iff ) x ) is 1|x|，thenitattainsitsmaximumvalueof1alueof1atx
Equivalently，if M is the maximum of f，thentheargmaxisthelevelsetofthemaximum 3360
ifthemaximumisreachedatasinglevalue，thenonereferstothepointastheargmax，meaningwedefinetheargmaxasapoint，notasetofpoints
(ratherthantheSingletonset (，sincethemaximumvalueofx(10x ) is 25，which happens when x=5.[note 2]
However，incasethemaximumisreachedatmanyvalues，arg max is a set of points。
Then，we have for example
sincethemaximumvalueofcos(x ) is 1，whichappensonthisintervalwhenx=0，2or4. onthewholerealline，theargmaxis { 0，2 }
argmin(orargmin ) is defined analogously。
notealsothatfunctionsdonotingeneralattainamaximumvalue，andhencewillingeneralnothaveanargmax : (nderset (x ) BBB ave x is undefined，asxisunboundedontherealline.however，bytheextremevaluetheorem (ortheclassicalcompactnessargument )，acontion