First of all, I wonder which result you expect. Is the result of “R mf pi%4” what you want?
Personally, I woldn’t mind if R’s shape reflects what we call a matrix as long as its result does (after all, you won’t be able to “matrix multiply gerund matrices”) So my solution would look like this: R2 =: ((cos , -@sin) ,. sin, cos) R2 pi%4 which yields the results I would have expected. Am 18.12.20 um 08:58 schrieb Francesco Pedulla': > 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 > -- ---------------------- mail written using NEO neo-layout.org ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
