Your solution is simple but does not easily generalize to more complex cases (infact, a requirement I did not express...). Thanks,
Francesco On Fri, Dec 18, 2020 at 6:18 PM Raul Miller <rauldmil...@gmail.com> wrote: > I would be tempted to use something like: > R=: (2 1,:1 2) o. _1 1&* > > For example: > R"0(0 30p1 45p1 60p1%180) > 1 0 > 0 1 > > 0.866025 _0.5 > 0.5 0.866025 > > 0.707107 _0.707107 > 0.707107 0.707107 > > 0.5 _0.866025 > 0.866025 0.5 > > FYI, > > -- > Raul > > On Fri, Dec 18, 2020 at 2:59 AM Francesco Pedulla' <mel...@gmail.com> > wrote: > > > > Dear all, > > I need to represent the 2D rotation matrix 'R' > > > > R = |cos(t) -sin(t)| > > |sin(t) cos(t)| > > > > and compute it for different values of the rotation angle 't'. I am aware > > the matrix of function can be represented as a gerund, which I like: > > > > R =: 2 2$cos`(-@sin)`sin`cos . > > > > To compute R(t), I wrote the following definition: > > > > mf =: conjunction : '($x)$,(,x)/.((+/$x)$y)' > > > > > > so that "R mf pi%4" returns R(pi/4). But I find the code for 'mf' not > very > > elegant. Is there a better way to achieve this? > > Thanks in advance for any hint, > > > > Francesco > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
