Thank you very much Peter, Indeed this should be left to the reader/practitioner. But I think -at least for the sake of comparison with matlab- we could have it in the core R. I would definitely try to learn more about R and implement it later.
Cheers, Ebrahim On Sun, Mar 11, 2012 at 11:56 PM, Peter Langfelder < peter.langfel...@gmail.com> wrote: > On Sun, Mar 11, 2012 at 1:46 AM, Ebrahim Jahanshiri > <e.jahansh...@gmail.com> wrote: > > Dear list, > > > > I understand that to raise matrix A to power (-1/2) we should use > something > > like this: > > > > eigen(A)$vectors%*%diag(1/sqrt(eigen(A)$values))%*%t(eigen(A)$vectors) > > > > [from previous discussions: > > http://r.789695.n4.nabble.com/matrix-power-td900335.html] > > > > But this will only do it for negative sqrt of the matrix not for other > > fraction powers like (-3/2). > > Not sure why you think this won't work for -3/2 - simply use > eigen(A)$values^(-3/2) instead of the 1/sqrt(eigen(A)$values) and > you're good to go. Generalizations to other powers are left as > exercise for the reader :) > > Peter > -- Ebrahim Jahanshiri Spatial and Numerical lab ITMA Universiti Putra Malaysia 43300, Selangor, Malaysia +60172002427 e.jahansh...@gmail.com -- Ebrahim Jahanshiri Spatial and Numerical lab ITMA Universiti Putra Malaysia 43300, Selangor, Malaysia +60172002427 e.jahansh...@gmail.com [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
