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]> 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]> 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] wrote: >>> >>>> Date: Tue, 16 Feb 2016 15:18:43 -0600 >>>> From: Kip Murray<[email protected]> >>>> To:"[email protected]" <[email protected]> >>>> Subject: [Jprogramming] A plane rotation >>>> Message-ID: >>>> <caofworgvydb1nmjwxkb0wosyfnlubxcdz20sv11uksfcfay...@mail.gmail.com> >>>> 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
