Not bad. I didn't know about r. . For clean I use clean =: (* *!.1e_14@|)"0&.+.
--Kip On Tuesday, February 16, 2016, Raul Miller <[email protected]> wrote: > Well... > > rottheta=: (rot~ r.)~ > 1r2p1 rottheta 3 4 > _4 3 > 1r4p1 rottheta _1 1 > _1.41421 1.11022e_16 > > I remember there being a concise phrase to clean irrelevant bits near > zero in a complex number, but I can't remember what I need to search > on to find it, and my foggy memory of how to write it is failing me at > the moment. > > Still, this gets you close. > > -- > Raul > > > On Tue, Feb 16, 2016 at 11:50 PM, Kip Murray <[email protected] > <javascript:;>> wrote: > > I'm retired with time to "fool around". Finding an old rot90 verb that > > used multiplication by a 2 by 2 matrix, I sought a more direct way using > > complex numbers and found one of the solutions that was posted. I also > > learned a lot from the other solutions posted, thanks everyone! > > > > New puzzle: find a complex analysis way to do a rotation given its angle > in > > radians, examples: > > > > 1r2p1 rottheta 3 4 > > _4 3 > > > > 1r4p1 rottheta _1 1 > > _1.414213562 0 > > > > --Kip > > > > I'm also a former math professor! > > > > On Tuesday, February 16, 2016, David Lambert <[email protected] > <javascript:;>> wrote: > > > >> > >> what's your agenda, are you writing a book? Isn't there a homogeneous > >> coordinate system/transformation lab? > >> > >>> > >>> On 02/16/2016 06:16 PM, [email protected] > <javascript:;> wrote: > >>> > >>>> Date: Tue, 16 Feb 2016 15:18:43 -0600 > >>>> From: Kip Murray<[email protected] <javascript:;>> > >>>> To:"[email protected] <javascript:;>" < > [email protected] <javascript:;>> > >>>> Subject: [Jprogramming] A plane rotation > >>>> Message-ID: > >>>> < > caofworgvydb1nmjwxkb0wosyfnlubxcdz20sv11uksfcfay...@mail.gmail.com > <javascript:;>> > >>>> Content-Type: text/plain; charset=UTF-8 > >>>> > >>>> Fairly easy: write a verb that rotates a point in the plane by the > angle > >>>> of > >>>> a given complex number. For example > >>>> > >>>> 1j1 rot 1 1 NB. Rotate 1 1 counterclockwise 45 degrees > >>>> 0 1.414213562 > >>>> > >>>> Background information: when you multiply two complex numbers the > >>>> magnitudes are multiplied and the angles are added. > >>>> > >>>> --Kip Murray > >>>> > >>>> > >>> > >> ---------------------------------------------------------------------- > >> For information about J forums see http://www.jsoftware.com/forums.htm > > > > > > > > -- > > Sent from Gmail Mobile > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm -- Sent from Gmail Mobile ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
