And array-set! for changing the value of an entry. /Jens Axel
Den søn. 7. okt. 2018 kl. 16.46 skrev Sam Tobin-Hochstadt < sa...@cs.indiana.edu>: > I think you want the `matrix-ref` function. > > Sam > On Sun, Oct 7, 2018 at 12:30 AM Ricardo Iglesias > <ricardoa.igles...@gmail.com> wrote: > > > > Sorry for the confusing wording. > > Basically, All I want is to be able to do > > G[ row ][ col ] = value > > > > In Racket. I've been messing with Racket this afternoon and have an > engine that is able to index into matrices, and just implemented several > common matrix operations, such as transpose, matrix multiplication, etc..., > so for now, I'm good. > > > > > > On Saturday, October 6, 2018 at 8:47:41 PM UTC-7, cwebber wrote: > >> > >> Ricardo Iglesias writes: > >> > >> > Good afternoon. I'm trying to move away from things like Matlab and > SciPy > >> > to do linear algebra work. > >> > Something I notice I do a lot is indexing operations, such as > >> > MATRIX[ row ] [ column ] > >> > > >> > I'm looking at the "math/matrix" library provided here: > >> > https://docs.racket-lang.org/math/matrices.html, and don't see > anything of > >> > this sort; I only see things like > >> > (matrix-map-rows) > >> > > >> > and > >> > (matrix-map-cols) > >> > > >> > Being able to access and modify a particular entry in the matrix > would be > >> > very useful in specifying operations to matrices. For example, given a > >> > matrix *G*, one might want to perform indexing operations to get the > matrix > >> > attached. > >> > > >> > Is this possible with the math/matrix library? > >> > > >> > Additionally, would there be a way to implement a version of > >> > matrix-map-row/cols that uses an index? > >> > >> Not quite what you're asking, but someone at RacketCon suggested to me > >> that maybe we should get GNU Scientific Library bindings added to > >> Racket, so we can better compete with Python and R for scientific / > >> statistical work... > > > > -- > > You received this message because you are subscribed to the Google > Groups "Racket Users" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to racket-users+unsubscr...@googlegroups.com. > > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- -- Jens Axel Søgaard -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
