Dear All,
Could someone give me some pointers (just a guide as to what functions I
need to look at would be fine)
as to how I go about this simple problem please;
The problem looks like this;
Choose x1 to x4 such that you minimize the MAXIMUM ABSOLUTE value returned
in the vector result of this matrix problem;
[x1,x2,x3,x4].[ -0.38 -0.52 0.68 -0.29 ]
[ -0.39 -0.42 -0.12 0.49 ]
[ -0.40 -0.20 -0.45 0.26 ]
[ -0.39 0.03 -0.39 -0.36 ]
I hope the formatting comes out ok , I did this on a Mac !
Glenn
[[alternative HTML version deleted]]
I'm not sure that it comes across as a "matrix problem" in the sense of involving matrix algebra, but it's also possible that I don't understand what you are saying. Seems that an appropriate application of: ?abs ?max ?sapply ?which.min ... ought to do the trick. If you were hoping for the name of the column vector, then may also need to look at: ?names -- David Winsemius On Jan 18, 2009, at 7:17 AM, glenn wrote:> Dear All, > > Could someone give me some pointers (just a guide as to what > functions I > need to look at would be fine) > as to how I go about this simple problem please; > > The problem looks like this; > > Choose x1 to x4 such that you minimize the MAXIMUM ABSOLUTE value > returned > in the vector result of this matrix problem; > > [x1,x2,x3,x4].[ -0.38 -0.52 0.68 -0.29 ] > [ -0.39 -0.42 -0.12 0.49 ] > [ -0.40 -0.20 -0.45 0.26 ] > [ -0.39 0.03 -0.39 -0.36 ] > > > I hope the formatting comes out ok , I did this on a Mac ! > > Glenn > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.
Hi Glenn, perhaps I'm misunderstanding your problem, but it seems to me that the zero vector (yielding a zero vector after the multiplication) will happily minimize everything you want. Apart from that, you may want to look at the Optimization Task View on CRAN. Good luck, Stephan glenn schrieb:> Dear All, > > Could someone give me some pointers (just a guide as to what functions I > need to look at would be fine) > as to how I go about this simple problem please; > > The problem looks like this; > > Choose x1 to x4 such that you minimize the MAXIMUM ABSOLUTE value returned > in the vector result of this matrix problem; > > [x1,x2,x3,x4].[ -0.38 -0.52 0.68 -0.29 ] > [ -0.39 -0.42 -0.12 0.49 ] > [ -0.40 -0.20 -0.45 0.26 ] > [ -0.39 0.03 -0.39 -0.36 ] > > > I hope the formatting comes out ok , I did this on a Mac ! > > Glenn > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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. >