search for: underdetermin

Hi, sorry, I'm an idiot.. and I know I'm missing something stupid.. I thought if we solve an underdetermine system with QR, my soln is: min ||x|| (L2 sense) such that Ax = b then say i have: > w <- matrix(c(1, 5), ncol=2) > sw = 2 > qrW = qr(t(w) %*% w) > qr.coef(qrW, t(w) %*% sw) [,1] [1,] 2 [2,] NA but we also have soln (0, 2/5) which obviously has a smaller distance in L...

Dear R users, I have to find optimal solution of an underdetermined linear system, but only with positive variables. I tried the function from this post https://stat.ethz.ch/pipermail/r-help/2007-October/143408.html , but it's solution includes also negative values. Thanks in advance. Best Regards. ------------------------------------- Майски празници...

...natural and distinguished solution x, the minimizer x which is itself of minimal Euclidean Norm. So if we want to return only one solution, I think we can agree that this should be it. In fact this very solution can be computed from the QR-decomposition of either A (overdetermined system) or t(A) (underdetermined system). I tried qr.solve on the underdetermined system Ax=b with b <- c(3,5,7) and A <- rbind( c(1,1,1,1,1), c(1,2,2,2,2), c(1,2,3,3,3) ) The system has infinitely many solutions. The minimal norm solution is x=c(1,0,2/3,2/3,2/3). But qr.solve(A,b) yielded the solution x=...

...are thought to account for one-third of global food production. How would you set about estimating the prevalence of waste with limited prior information (some survey-based data are available) taking stock of the determinants of phenomenon -How can prior information be used to specify and estimate underdetermined systems of equations Please reply to: Adam.Prakash at fao.org. Best regards Matthieu Stigler [[alternative HTML version deleted]]

hi there, does anyone know how to calculate the amount of daylight on every day of the year in R? I mean the time between sunrise and sunset. thanks -- View this message in context: http://r.789695.n4.nabble.com/daylight-tp4647213.html Sent from the R help mailing list archive at Nabble.com.