search for: overdetermined

Displaying 12 results from an estimated 12 matches for "overdetermined".

2004 Apr 27
3
Solving linear equations
Is there a simple method under R to solve an overdetermined system of linear equations Ax=b with A being a matrix m*n? I know that solve() seems to work for m*m matrices, but I had no luck with overdetermined systems. Mlod
2017 Jun 29
0
package to fit mixtures of student-t distributions
Offlist, because this is (a) an opinion and (b) about statistics and therefore offtopic. I don't know whether any such package exists, but I would predict that this is likely to be overdetermined (too many parameters) and therefore unlikely to be a successful strategy. Fitting a mixture of Gaussians is already difficult enough. Feel free to ignore, of course, and no need to reply. Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and s...
2017 Jun 29
1
package to fit mixtures of student-t distributions
...t; On 29. Jun 2017, at 16:58, Bert Gunter <bgunter.4567 at gmail.com> wrote: > > Offlist, because this is (a) an opinion and (b) about statistics and > therefore offtopic. > > I don't know whether any such package exists, but I would predict that > this is likely to be overdetermined (too many parameters) and > therefore unlikely to be a successful strategy. Fitting a mixture of > Gaussians is already difficult enough. > > Feel free to ignore, of course, and no need to reply. > > Cheers, > Bert > > > Bert Gunter > > "The trouble wit...
2019 Aug 13
0
behaviour and documentation of qr.solve
...norm. There is then exactly one 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.sol...
2007 Oct 16
1
underdetermined system
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
2009 Jan 25
1
Delete Dates from a vector.
I need to create a vector of dates, weekdays only for a function I am working on. Thanks to the chron library, I have managed to accomplish this, but is there is a better / easier way. This is what I have thus far. range.dates <- seq.dates('02/02/2009', '03/13/2009', by = 'days') range.days <- weekdays(range.dates) weekends <-
2009 May 11
1
Building US maps in R
Hi, I'm trying to build some maps of the US by county that will have the following characteristics: Feature/Map Map 1 Map2 Both Broken out by county Yes Yes Yes Heatmaps of US Census Data for income by county Yes No Yes Heatmaps of US Census Data for race by county (recoded as white and &non-white, with each county color coded based on the majority) No Yes No Polygon
2017 Jun 29
6
package to fit mixtures of student-t distributions
Hello! I am new to R (before used python exclusively and would actually call the R solution for this issue inside a python notebook, hope that doesn?t disqualify me right of the batch). Right now I am looking for a piece of software to fit a 1D data sample to a mixture of t-distributions. I searched quite a while already and it seems to be that this is a somehwat obscure endeavor as most
2005 Jun 14
1
Matrix stability problem
Hello, This is not a problem with R, the calculated results are mathematically correct. This a matrix stability problem. Because of measuring errors, my matrix solution is a bit off. Here is what my equations look like: A11 x11+A12 x12 +A13 x13 = b1 A21 x21+A22 x21 +A23 x23 = b2 A31 x31+A32 x31 +A33 x33 = b3 A is a reading, X is a measured weight, and b is total. The 3 experiments give
2008 Nov 08
3
New to List - just starting to learn R - question about reading in data
Hi, everyone, I'm new to R and the List, and excited to be here. I am coming from a background working in SPSS 16, primarily, which has a lot of easy options for reading in data. I am working in R in an Ubuntu Linux environment, and I'm learning with R Commander. Now, here's my question. In my line of work, I'm used to getting data in some kind of flat ASCII format with a
2009 Jan 15
2
Interface to open source Reporting tools
...> Message-ID: > <2ad0cc110901101150t191458f7j9d16eb076f42e30d@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > The reactions to the NYT article have certainly made for some > interesting reading. > > Here are some of the links: > > http://overdetermined.net/site/content/new-york-times-article-r > > http://jackman.stanford.edu/blog/?p=1053 > > http://ggorjan.blogspot.com/2009/01/new-york-times-on-r.html > > several posts on Andrew Gelman's blog: > http://www.stat.columbia.edu/~gelman/blog/ > > > http://www.reddit.c...
2009 Jan 18
1
Error installing ggobi in R, Ubuntu Intrepid Ibex
Hi, I'm newish to R and Ubuntu, and I've getting this error when I'm trying to install ggobi in R. Any suggestions? DD *R version 2.7.1 (2008-06-23) Copyright (C) 2008 The R Foundation for Statistical Computing ISBN 3-900051-07-0 R is free software and comes with ABSOLUTELY NO WARRANTY. You are welcome to redistribute it under certain conditions. Type 'license()' or