Apparently, this user prefers to keep an air of mystery about them.
3 When computing the Taylor series of $(\cos x)^2$ how does the slide jump to concluding it is $1-(\sin x)^2$? may 27 '13
1 Given a singular covariance matrix of a random vector $X=[X1,X2,X3,X4]$, how do I partition $X$ into 2 parts to get a non-singular covariance matrix? nov 25