Hi Ben, in fact you got the point. I thought you needed a gerund to build a structure of functions. Your solution is very clean and I like it a lot. Thanks!
Francesco On Fri, Dec 18, 2020 at 12:56 PM Ben Gorte <bgo...@gmail.com> wrote: > Perhaps I'm missing the point, but I would say: > > R =: ((cos , -@sin) ,: sin , cos) > > R 1r6p1 > > 0.866025 _0.5 > > 0.5 0.866025 > > > Ben > > On Fri, 18 Dec 2020 at 18:59, 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
