Hi Sorawee, > On Feb 17, 2021, at 3:20 PM, Sorawee Porncharoenwase > <sorawee.pw...@gmail.com> wrote: > > Hi John, > > A couple of questions: > > Although that’s how I ended up here, my actual problem came when I thought > “oh, I could just add this to my local copy of the number-theory package, and > test whether my implementation is faster or slower than modular-expt.” > > I don’t understand why you need to “add this to … local copy of the > number-theory package”? If you want to compare your version with the math > package’s version, you can do something like > Yes, I understand that (now). Originally, I used (time…) as you mentioned below, but for my function, I didn’t need to import anything (not even ‘loop’) so I noted that the (require …) would add time to the execution of modular-expt (it did). So for closest comparison, I wanted to put them in the same package. And, I wanted to put mine in github too, so forking racket/math made sense to me as good a place as any to put this. > #lang racket > > (require math/number-theory) > > (define (my-modular-expt a n) ...) > > (time (my-modular-expt ...)) ; test your version > (time (modular-expt ...)) ; test the `math` package's version > In fact, by modifying the math package, you will no longer have the math > package’s version to compare to! > > Slightly off-topic: do you find that the math package’s version is too slow? > No I don’t. I was experimenting with modulo/expt, and I looked at modular-expt and saw that it was not using the bit-shift mechanism, so I decided to implement that. That’s all.
> Why did you try to implement your own version in the first place? > Just as a learning exercise… I didn’t see any obvious performance difference, but I guess if I compare the two implementations, I would say: 1. modular-expt uses infix operators (which looked strange to me in Racket context FWIW but is clearly just my personal taste). 2. modular-expt uses the ‘loop’ syntax (taking an extra dependency that seems not needed for a bitwise shift to get equivalent performance). I’m not suggesting that my implementation is better than what you’ve done already. I just followed my interest in learning how to implement what I did. - johnk > Best, > > > On Tue, Feb 16, 2021 at 5:24 PM Robby Findler <ro...@cs.northwestern.edu > <mailto:ro...@cs.northwestern.edu>> wrote: > I would not do it quite that way. Here's the steps I recommend: > > git clone https://github.com/racket/racket.git > <https://github.com/racket/racket.git> > cd racket > make # get some coffee here > mkdir extra-pkgs > cd extra-pkgs > # make sure `raco` in your path is the one you built just above > raco pkg update --clone math > > .... now do git stuff / racket stuff. > > The upside to avoiding the "PREFIX=..." is that the racket installation is > now completely contained in that directory. Just throw it away when you're > done with it and if you have more than one (perhaps you want to try out an > older version or a released version or something) all you have to do is > update your path. And if you want to update to get some bug fix or > improvement, simply do a git pull and make in the top-level directory again. > (That "make" really does include all of the steps, like it'll run configure > and do all kinds of things so you don't have to worry about it.) And the > "extra-pkgs" directory is just the convention some of us use. > > Robby > > > On Tue, Feb 16, 2021 at 7:10 PM John Kemp <stable.pseudo...@gmail.com > <mailto:stable.pseudo...@gmail.com>> wrote: > > On Feb 16, 2021, at 3:49 PM, Robby Findler <ro...@cs.northwestern.edu > > <mailto:ro...@cs.northwestern.edu>> wrote: > > > > I think you probably want to use "raco update --clone math" and you'll end > > up with a directory named "math": where you run that that is a clone of the > > racket/math github repo and the racket installation you ran "raco" from > > will now use that as the source. Then you can add a remote to it with your > > clone to work on a pull request. You should be able to do this with your > > own built version of racket (which you get by running "make" in the top > > level of a clone of racket/racket) or in a snapshot build or probably even > > in 8.0. > > > > Does that help? > > Thanks Robby, that definitely helped (although I’m not finished getting this > to work). > > Checking the correct sequence: > > 0. cd ~/src > 1. git clone https://github.com/racket/racket.git > <https://github.com/racket/racket.git> > 2. cd racket && make PREFIX=/usr/local > 3. cd .. && /usr/local/bin/raco pkg update —clone math (this worked FWIW and > cloned the math collection to my ~/src directory) > 4. cd racket && make PREFIX=/usr/local (to install the updated math package > into this copy of racket) > 5. /usr/local/bin/racket (to test changes in REPL) > > In my case, I think part of my problem was a) two copies of Racket installed > (so I needed to be more specific about which raco to use) and b) not > understanding where raco is doing its work. > > Cheers, > > - johnk > > > > > Robby > > > > > > On Tue, Feb 16, 2021 at 2:36 PM John Kemp <stable.pseudo...@gmail.com > > <mailto:stable.pseudo...@gmail.com>> wrote: > > Hi there, > > > > I implemented an alternative to the modular-expt function in the > > math/number-theory package, that uses bit-shift > > (https://gist.github.com/frumioj/2dcc1364464508ec359075d5014d0157 > > <https://gist.github.com/frumioj/2dcc1364464508ec359075d5014d0157>), as > > proposed by Bruce Scheier (pseudocode in > > https://en.wikipedia.org/wiki/Modular_exponentiation > > <https://en.wikipedia.org/wiki/Modular_exponentiation>). > > > > Although that’s how I ended up here, my actual problem came when I thought > > “oh, I could just add this to my local copy of the number-theory package, > > and test whether my implementation is faster or slower than modular-expt.” > > > > First, I forked the github racket/math repo, and couldn’t see a way to > > build that independently of Racket. So then I checked out the racket repo > > itself, which uses raco to get me a copy of the math package collection. I > > was able to build with that, but it seems unconnected to the github > > racket/math repo. > > > > I tried various raco incantations to see if it were possible to get a copy > > of my forked math package, but nothing seemed to work, and I am concerned I > > misunderstood the instructions in > > https://docs.racket-lang.org/racket-build-guide/index.html > > <https://docs.racket-lang.org/racket-build-guide/index.html> > > > > Is there any document that describes how I should be able to both build and > > use a local math/number-theory package, and also be able to use my forked > > copy of that repo to commit my changes? Is it possible for me to *only* > > check out racket/math and build it for my local Racket installation? > > > > Thank you, > > > > - johnk > > > > -- > > You received this message because you are subscribed to the Google Groups > > "Racket Developers" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to racket-dev+unsubscr...@googlegroups.com > > <mailto:racket-dev%2bunsubscr...@googlegroups.com>. > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/racket-dev/E30EA0E9-DC7F-498C-9F67-42554EBB757E%40gmail.com > > > > <https://groups.google.com/d/msgid/racket-dev/E30EA0E9-DC7F-498C-9F67-42554EBB757E%40gmail.com>. > > > -- > You received this message because you are subscribed to the Google Groups > "Racket Developers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-dev+unsubscr...@googlegroups.com > <mailto:racket-dev+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-dev/CAL3TdONM%3DGm_t%3DO_X%3D%3DOcR1oj94yTXnSJ8zp3hU3OQ-qsFN2BA%40mail.gmail.com > > <https://groups.google.com/d/msgid/racket-dev/CAL3TdONM%3DGm_t%3DO_X%3D%3DOcR1oj94yTXnSJ8zp3hU3OQ-qsFN2BA%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "Racket Developers" group. 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