One issue is that we need #@:+ instead of #@+ in earlier J versions. Thanks,
-- Raul On Sun, Oct 18, 2020 at 5:45 AM 'Michael Day' via Programming <[email protected]> wrote: > > Looks neat. I think it has to be square, and it doesn't need to be > non-singular: > eg, > > Here, y = x is a straight line, and 5 data points overspecify it! ... > > (,:(X np X)&p.) steps _1.5 1.5 5 > > _1.5 _0.9 _0.3 0.3 0.9 1.5 > > _1.5 _0.9 _0.3 0.3 0.9 1.5 > > > Oddly enough, I tried it out first on my iPad, running J701. On that > > tablet I got : > > > ~. X np Y in J701/iPad !!! ~. to save lines > _14.1014 > > I thought that was it for discrepancies. I haven't kept J7.01 on the > laptop, > > but I do still have J8.07. I've just checked and find the same result > there! > > > JVERSION > > Engine: j807/j64/windows > > Release-e: commercial/2019-11-04T09:51:03 > > Library: 8.07.26 > > Qt IDE: 1.7.9/5.9.6 > > Platform: Win 64 > > Installer: J807 install > > InstallPath: c:/d/j807 > > Contact: www.jsoftware.com > > > ~. X np Y NB. in J807... > _14.1014 > > Old J - odd/old results. I expect others will see why, > > > Cheers, > > > Mike > > > > On 17/10/2020 23:10, Raul Miller wrote: > > For what it's worth, here's an example of a "quite straightforward" > > translation of the original 'np' to tacit form (assuming that the > > newton matrix is always square -- I didn't spend enough time studying > > here to feel comfortable leaving that assumption unstated, though I > > did force a length error should that not be a valid assumption): > > > > NB. divided differences > > dd=: (2 -~/\ ]) % [ ({: - {.)\~ 2 + -&# > > > > NB. Coefficients are the topmost entries > > np=: [: {."1 dd ^:(i.@#@+) > > > > X=: _3r2 _3r4 0 3r4 3r2 > > Y=: 3 o. X > > load'plot stats' > > plot(;(X np Y)&p.) steps _1.5 1.5 30 > > > > I hope this helps, > > > > > > -- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
