Hi, how about this: mm<-cbind(V1,V2) xy<-sapply(1:3,function(x)det(mm[-x,])*(2*(x%%2)-1))
#some checks all.equal(0,as.vector(xy%*%V1)) all.equal(0,as.vector(xy%*%V2)) Am 08.07.2011 08:27, schrieb Bai: > Hi, everyone, > > I need an efficient way to do vectors cross product in R. > > Set vectors, > V1 = ai + bj + ck > V2 = di + ej + fk > > then the cross product is > V1 x V2 = (bf - ce) i + (cd - af) j + (ae - bd) k > > > As shown here ( http://en.wikipedia.org/wiki/Cross_product ). > > Thanks. > > Best, > Bai > > ______________________________________________ > 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. -- Eik Vettorazzi Institut für Medizinische Biometrie und Epidemiologie Universitätsklinikum Hamburg-Eppendorf Martinistr. 52 20246 Hamburg T ++49/40/7410-58243 F ++49/40/7410-57790 ______________________________________________ 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.
