A题协方差阵的理解？

helloj2ee

如果是n个node，协方差阵为什么是n(n-1)/2 square matrixs,在这里n(n-1)/2到底表示的是什么意思？

zhudy

协方差阵的阶数是由节点数决定的，如果有n个节点最大的边数是n(n-1)/2,任意两边的行车时间之间有协方差，因此，矩阵是n(n-1)/2阶。

农民也建模

<>但题中说每行或每列有n(n-1)条links:  then the time dependent function Cov(ij,kl) is a n(n-1)/2 sqaure matrix, each row or column representing a link 12,…,1n,21, …,2n,…n1,n2,… n(n-1).</P>
<>如何解释???</P>

zhudy

自己理解

bzc2008

<FONT face="宋体, MS Song"> It is assumed that travel time follows the same rule as question 1, average link travel time is proportional to link length, variance of link travel time is proportional to the reciprocal of  as well as proportional to the product of the number of links connecting to the two nodes at both ends of the link.<v:shapetype><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path connecttype="rect" gradientshapeok="t" extrusionok="f"></v:path><lock aspectratio="t" v:ext="edit"></lock></v:shapetype><v:shape><v:imagedata></v:imagedata></v:shape></FONT>