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The Mathematica Journal: Mathematica Techniques and Applications 搜索引擎 « 搜索技术博客-淘宝 外贸直通车,即国际站P4P,是让阿里巴巴的ICBU会员企业(后面也会对免费的认证会员开放)更好的推广其产品的一种增值业务。在此业务系统中,卖家可以自主地选定要推广的产品和添加购买关键词,然后在买家用户搜索关键词或类目浏览时免费优先展示其产品信息并通过大量曝光来吸引潜在买家,并最终按照用户点击来付费。 在总体技术架构上,国际站P4P包含几个重要的子系统和模块.它们之间的交互关系如下图所示: 其中,每个子系统的主要功能为: BP(Business Platform) BP系统是重要的后台支撑系统。 iMatch引擎 iMatch引擎是重要的广告offer的在线查询系统。 算法模块和服务 算法主要负责扩展匹配、广告质量(mlr)以及预估点击转化率(ectr)等模型的训练和建立,并以库的方式提供给iMatch引擎使用。 SW(Search Web) SW应用负责根据各个布点的要求请求iMatch引擎得到相应的广告offer并展示他们。 DA(Data Application) DA系统主要负责收集各种log,包括PV log和点击日志,然后进行按小时和全天的数据分析得出各种报表数据供我们自己分析和用户查看。 简介 目前国际站P4P iMatch引擎是基于iSearch 4.2.1开发的一套分布式广告搜索引擎系统。 作为一个可扩展的分布式广告引擎系统,iMatch引擎主要包含如下的几个模块: 下面分别介绍上图中每个模块的主要功能和实现. 离线全量索引构建 离线全量build索引是实现在线搜索查询的基础和前提,它线下批量分析每个offer、match和keyword等信息然后构建成isearch引擎的索引供在线查询使用。 新的dump系统首先会全量dump BP数据系统里面的数据,然后基于Erosa/Eromanga做到准时候的同步BP数据库中的各种增、删、改、查的变更操作,将修改操作写入到HBase中。 在全量的时候,相关数据会被从HBase表中取出来进行join操作,从而生成用于建索引的xml文件。 所以,整体上离线索引构建系统的处理流程图如下图所以: 实时增量索引构建 P4P的实时增量消息是直接对接BP的iNotify系统的。 当用户在BP系统进行各种变更操作时,比如添加offer,添加购买词和修改购买词价格等操作,BP在修改数据库的同时会将这些变更以消息的形式实时发给引擎的dispatch服务。

MathBin.net - Math pastebin for equation rendering xkcd The Maths behind "NUMB3RS" LARRY (cont'd) At the request of the bride and groom, I will keep my remarks short and non-technical. As you know, there are four fundamental forces in physics: electromagnetism, strong nuclear interaction, weak nuclear interaction, and gravity. The liquid-drop model in nuclear physics was originally proposed by George Gamow and developed by Hans Bethe and Carl von Weizsäcker in the 1930s. It treats the nucleus as an incompressible fluid of protons and neutrons bound together by the strong nuclear force. It treats the nucleus as an incompressible fluid of protons and neutrons bound together by the strong nuclear force. LARRY Social network models interpret the structure of human relationships: social, economic, political. The adjacency matrix of a graph shows how the vertices are connected; when the entry at row i, column j is 1 in the matrix, the vertices i and j are connected. CHARLIE You know the "Six Degrees of Separation" phenomenon?

The Mathematica Book Online: 循环控制结构 程序的执行涉及到一系列表达式的计算,在简单程序中, 由;分开的表达式将逐个计算,但在一些循环中,某些表达式可能 被计算多次. 简单循环结构 i 从 1 到 4 计算 Print[i^2] In[1]:= k 从 2 到 6 ,增量为 2,对 t 进行赋值 In[2]:= Out[2]= Do 中定义的循环方式和函数 Table 和 Sum 中的相同,与这些函数类似, 可以使用 Do 循环嵌套. i 从 1 到 4 循环,对每一个 i ,j 从 1 到 i-1 循环 In[3]:= 有时需要进行某一个运算多次,但还不希望改变迭代变量的值, 可以用如 Table 和其它迭代函数中使用的类似方法在 Do 循环中实现 这一要求. 重复赋值 t = 1/(1+t) 3 次 In[4]:= Out[4]= 可以在 Do 循环中使用过程 In[5]:= 重复使用函数 Do 对迭代变量的不同值反复计算一个表达式,使用户能进行重复运算. 这里函数 f 迭代 3 次 In[6]:= Out[6]= 对纯函数迭代,也能得出前面用 Do 函数一样的结果 In[7]:= Out[7]= Nest 可以重复运用函数若干次,用时要反复使用函数直到结果不再改变为止, 这可以用 FixedPoint[ f , x ] 来实现. FixedPoint 重复使用函数直到结果不再改变为止 In[8]:= Out[8]= FixedPoint 可用来模仿 的计算过程或 等函数运算. 计算的非局部控制 遇到 Throw 时停止计算, Catch 的返回值是 i 的当前值 In[9]:= Out[9]= Throw 和 Catch 提供了计算控制的又一方式,当遇到 Throw 后计算过程停止, 就返回到最近的一个 Catch. Scan 使用 Print 函数在每个元素上,最后返回值为 Null In[10]:= 遇到 Throw 后 Scan 的计算结束,所含的 Catch 返回值是 Throw 变量的值 In[11]:= Out[11]= 用 Map 也可以得到同样的结果,当计算过程不是遇到 Throw 时结束, Map 的返回值是一个集合 In[12]:= Out[12]= 用 Throw 和 Catch 可以改变函数编程结构,使得计算过程到一定条件出现时结束. 反复使用一个函数得到的集合 In[13]:= Out[13]= 由于没有遇到 Throw ,所以结果与前面相同 一般的循环结构

EPIK.SCIENTIFIK.FR Greg Mankiw's Blog Stephen Wolfram Stephen Wolfram (born 29 August 1959) is a British scientist,[7] known for his work in theoretical physics, as the chief designer of the Mathematica software application and the Wolfram Alpha answer engine, as well as the CEO of Wolfram Research, and the author of A New Kind of Science.[2][8][9][10][11][12][13] Background[edit] Wolfram's parents were Jewish refugees who emigrated from Germany to England in the 1930s.[5][14] Wolfram's father Hugo was a textile manufacturer and novelist (Into a Neutral Country) and his mother Sybil was a professor of philosophy at the University of Oxford.[15] He has a younger brother, Conrad Wolfram.[16] Wolfram is married to a mathematician and has four children.[17] Education[edit] Wolfram was educated at Eton College, but left prematurely in 1976. Career[edit] Following his PhD, Wolfram joined the faculty at Caltech and received one of the first MacArthur Fellowships in 1981, at age 21.[18] Research[edit] Unpublished works[edit] Particle physics[edit]

Newest Questions - Mathematica current community your communities Sign up or log in to customize your list. more stack exchange communities Stack Exchange sign up log in tour help Mathematica Ask Question All Questions newest 1 featured frequent votes active unanswered votes 0answers 11 views Shooting method can someone look at my equations , and tell me how would I simulate it? equation-solving differential-equations matlab asked 33 mins ago user1675947 1 6 views “NotebookPredictions” I have deleted mathematica user folder, as well as reinstalled mathematica but I keep getting error message: The front end encountered an error while processing a "NotebookPredictions" packet. error-messages error asked 52 mins ago 2answers 24 views X-Y scatterplot Hi I have a simple question. plotting asked 1 hour ago Palaeoanth 61 1answer 12 views Matrix Operation I have a 3\times3 matrix A, and a function sTrans that outputs two 3\times3 matrices in a list when given a 3\times3 ... list-manipulation data-structures Alex Su 1274 40 views

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