The rank of a matrix (in the linear algebra, not J sense) is tricky to determine numerically because of stability issues: an arbitrarily small perturbation may increase the rank. A good practical start is the singular value decomposition, available through the LAPACK extension. This reduces the problem to finding the rank of a diagonal matrix.
Best wishes, John > On Jan 13, 2022, at 2:53 PM, Pawel Jakubas <[email protected]> wrote: > > Dear J enthusiasts, > > I am wondering what is the preferable way to determine the rank of a matrix > in J. > I would expect here below > > ]m=: 3 3 $ 1 2 3 5 4 6 9 7 8 > 1 2 3 > 5 4 6 > 9 7 8 > rank m > 3 > > ]m=: 3 3 $ 1 2 3 2 4 6 9 7 8 > 1 2 3 > 2 4 6 > 9 7 8 > rank m > 2 > > Thanks and cheers > Pawel Jakubas > ---------------------------------------------------------------------- > For information about J forums see > https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.jsoftware.com%2Fforums.htm&data=04%7C01%7Crandall%40newark.rutgers.edu%7C880d6cd5d64e4e90976208d9d6ce1893%7Cb92d2b234d35447093ff69aca6632ffe%7C1%7C0%7C637777003825756175%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=pwibQz9Jk2T4mmkbJ%2FTVp6YgUGhZRVCZx8KUTVEppIc%3D&reserved=0 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
