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Using Snow from Gambit?
by Paul Onions 03 Mar '09

03 Mar '09

This may be a dumb question (I'm new to Gambit, and have just discovered Snow), but is there a way to access Snow packages from Gambit? e.g. if I start a Gambit REPL with gsi, is there a way to "(require XXX)" which will then load the package XXX into my Gambit environment? I have downloaded and installed the snow-generic release, using Gambit as host, and can use snowman to download and install packages, but I seem to be missing the "big picture", that is, how do I actually *use* these packages? Hope somebody can enlighten me, Paul

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objective c / cocoa / mac osx / gambit
by lowly coder 02 Mar '09

02 Mar '09

Hi! Is anyone here doing OSX / Cocoa / Objecive-C development using Gambit? If so, can you point me to some good pointers? I'm mainly from the C / Linux / OpenGL land -- and I'm quite unfamiliar with how Gambit bindings on OSX end up working (especially with the Objective-C interaction). Thanks!

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Problem with make check
by Paul Onions 28 Fév '09

28 Fév '09

Hello, When building from the latest GIT sources, running "make check" I get: ------------ TEST 5 (compiler generating C code) rm -f mix.c ../gsc/gsc -:~~bin=../bin,~~lib=../lib,~~include=../include -f -c mix.scm diff test5.ok mix.c 1780c1780 < ___DEF_SUB_FLO(___X17,-0x1L,-0x1L) --- > ___DEF_SUB_FLO(___X17,0x7fffffffL,-0x1L) make[1]: *** [test5] Error 1 make: *** [check] Error 2 I'm running MACOSX 10.5 on a PowerPC machine. Should I be concerned about this? Thanks, Paul

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update?
by Bradley Lucier 28 Fév '09

28 Fév '09

Marc: What? 24 hours without an update? Brad

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debugging macros
by lowly coder 27 Fév '09

27 Fév '09

(define-macro (define-cool-macro decl . body) `(begin (define-macro ,decl ,@body) (define-macro ,(cons (string->symbol (string-append (symbol->string (car decl)) "-dbg")) (cdr decl)) ,@body))) (define-cool-macro (fn . body) `(lambda ,@body)) (pp (fn-dbg (x) (+ x 2))) Now, does anyone see anything wrong with define-cool-macro, or some way/something that may resulted in unexpected sideeffects (along the lines of accidently introducing variables in macros). Thanks!

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define-type and define-record-type
by Pavel Dudrenov 27 Fév '09

27 Fév '09

I keep seeing references to those in code samples all over gambit written code. What do they do exactly? I think I know, but they seem to take a plethora of keywords as well constructor:, extender:, implementer: etc. Sorry about the noise, Pavel P.S. These are somewhat documented on the wiki, but most of the keywords they take are undocumented.

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Re: [gambit-list] copy-file on windows & links
by Christoph Bauer 26 Fév '09

26 Fév '09

Hi, > I have a question concerning copy-file on windows. > my setup: filesystem on linux mounted over samba on windows I > try to copy a file with "copy-file", which is acutaly a > symlic link under linux. > This results in a .lnk-file. Is there a way to make a real > copy of the file? sorry for the noise, but I think the source of my problem comes from elsewhere. How could I suspect gambit? Christoph Bauer

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optimizing computer simulations of the Ising model
by Marijn Schouten (hkBst) 26 Fév '09

26 Fév '09

Hi Gambitters, I want to use Scheme to implement a computer simulation of the Ising model of spins. Background: http://en.wikipedia.org/wiki/Ising_model Basically all the algorithm does is allocate a vector of spins and flip them randomly in such a way that a representative sampling at a specified temperature is produced. Efficiency of the algorithm is very important as it would allow me to study larger samples. Currently on my own system after compilation: with a sample size of 40x40 I can do 1000 flips/site in a little over 3 seconds. Currently the simulation starts from an all up state and displays some variables and the end configuration of the sample. It looks like this: $ time gsi ising -e "(main 1000)" D: 2, N: 1600, L: 40, BETA*J: .3, RANDOM-STATE: 10624525222961816100342112271285465503733219408383542344109 E: 72, M: -40 +-++++---++---+-+-+-++++--+----+++-+-+-- +++-+---+-+------++---+-+--+--+++++++--- ----+-+--+--+-+--+-+-+++-++---------++-+ ---+---+--++-++++-++++-+--+++-++---+--+- ++++--++-+----++++----+-++---+----+-+++- -----+++--+---+-+++++-++++-+---+++-+++-+ ++-+--+-+---+--+++++-+-+---+++++-++---+- -+---+--++--++--+---++++--+-----+-+-+--+ ----+-+--+---++--+-++-+--+----+++---++-- --++-++---+-++++--+++-++++----+-+++++--- ++-+-+-+-+-+++-+-++++++-+---+---++-+-+-- +--+---++-++++----+-++-+-+-++-++-------+ +--------+++-+-+++---+-+--+-+---++--+-++ +---++-+-+++++++--+-++--+-+++-++++---++- +--+----+++--+--+-+---+++-+-+---+--+++++ ++-+++-+++--+++--+-++++--++-+---+-+-++++ +-+---+++--+-+--+++-+--+---+-++++++-+++- ++---++---+-+--++-+++----+-+++--+++-+--- ++-++-+--+---+++-----+-+----+--+-+-+-+-+ ++--++--+--+-+++--++++--+++++--++-+--+-+ -+---++--+-++--++-+--++-+-++--+-++++-+-+ +----+-+--+++--+---+--+-+++--++--++-+++- ++++--+-++--++++----+-++-+--------+-++++ +-----+++++++-+-+--++-++-+--+++--++-++++ +--++-+-++-------+-+++-----++-+-++-+-++- +--+++--+-+++--+---+---+-----++-+-++-+++ --+-+-+---+-+++----+-+--------+----+-+-+ -+--+--+-+++-+-----+-+----++++-++-++-++- -+-++-+-+--+--+----+++--+-+-+-++--+++-+- +-+++-+-++-+-+++++-+----+-+-+--+-++----+ +------+-+---+-++-+-++++-++-++-++---++-+ ++----++-+-+--+-+-+++-+-+---+++-----++-+ ++++-++++-++-+-+++--++++-++-+--+++++-++- ++-----+++++--++--+-+-+-++-+-+++------+- ++++-+++---+---+-+-++-+---+-+----++++--+ +---++--++---++-+----------+-----+---++- ---++-++--+--++--+--++-+----+--+-++----+ ++--++--+--++++-+---++-++------++-++---- -++-++-++-++---+----+-++---++++++--++-++ +-----+++++--++-+-+---+-++---+-++--++-+- real 0m3.507s user 0m3.198s sys 0m0.007s to compile the program I use: gsc -cc-options "-O2 -march=native" ising I do not know enough about Gambit to know what's fast and what's not and I have no experience with profiling, so I would appreciate some pointers on how to go about optimizing the program. As a side note I was also hoping to compare the performance of various Schemes for this workload, but it seems the ones I tried so far (bigloo and guile) do not support srfi-27 (Sources of Random Bits) much. (It worked in guile until just now when I added a few bits to be able to change the pseudorandom number generator seed.) If anyone knows other implementations where it would run that would be cool. Finally, the source is attached. Any comments appreciated. Thanks in advance, Marijn -- Sarcasm puts the iron in irony, cynicism the steel. Marijn Schouten (hkBst), Gentoo Lisp project, Gentoo ML <http://www.gentoo.org/proj/en/lisp/>, #gentoo-{lisp,ml} on FreeNode ;;;calling ; $ gsc -cc-options "-O2 -march=native" ising ; $ time gsi ising -e "(main 1000)" ;;;end calling ;;;compatibility ;bigloo compat ;(define random-integer random) ;bigloo has no random real generator!!! (define (random-real n) (random ?)) ;guile compat ;guile does not support srfi-27 enough (define random-integer random) (define random-real random:uniform) ;;;end compat (define (SPIN+) +1) (define (SPIN-) -1) ;;; coupling constant (define J 1) ;ferromagnet ;(define J -1) ;antiferromagnet ;;; inverse temperature times coupling constant (define (BETA*J) 0.3) ;(define (BETA*J) 0.4) ;(define (BETA*J) 0.5) (define (display-spin spin) (cond ((= spin (SPIN+)) (display "+")) ((= spin (SPIN-)) (display "-")) (#t display "?"))) ;;; sample length in one dimension (define L 40) ;;; sample dimension (define D 2) ;;; total number of spins ;;; if this is a power of 2 ;;; then modulo can be fast (define N (expt L D)) ;round N down to power of 2 ;(set! N (expt 2 (inexact->exact (floor (/ (log N) (log 2)))))) (define GRID (make-vector N (SPIN+))) (define (display-spatial-sample grid) (let loop ((site 0)) (cond ((< site N) (display-spin (vector-ref grid site)) (if (= (- L 1) (modulo site L)) (newline)) (loop (+ 1 site))))) (if (not (= (expt L D) N)) (newline)) (newline)) (define (display-sample grid) (for-each display-spin (vector->list grid)) (newline)) (define (dimension-loop site kons) (let loop ((d 0) (ret '())) (cond ((< d D) (loop (+ 1 d) (kons d site ret))) (#t ret)))) ;;;helical boundary conditions (define (helical-neighbors site) (dimension-loop site (lambda (d site ret) (cons (modulo (+ (expt L d) site) N) (cons (modulo (- site (expt L d)) N) ret))))) (define (helical-plus-neighbors site) (dimension-loop site (lambda (d site ret) (cons (modulo (+ (expt L d) site) N) ret)))) ;;; Metropolis => equal probabilities for each transition (single-spin-flip) (define (random-site) (random-integer N)) (define (flip! grid site) (vector-set! grid site (* -1 (vector-ref grid site)))) (define (energy-jump/J grid site) (* 2 (vector-ref grid site) (apply + (map (lambda (n) (vector-ref grid n)) (helical-neighbors site))))) ;;; Metropolis => always accept energy-lowering transitions (define (accept-flip grid site) (if (> 0 (energy-jump/J grid site)) #t (< (random-real) (exp (* (BETA*J) (energy-jump/J grid site)))))) (define (single-spin-flip! grid) (let ((site (random-site))) (if (accept-flip grid site) (flip! grid site)))) (define (magnetization grid) (apply + (vector->list grid))) (define (energy/J grid) (define (-energy/J-plus site) (* (vector-ref grid site) (apply + (map (lambda (n) (vector-ref grid n)) (helical-plus-neighbors site))))) (let loop ((s 0) (E 0)) (cond ((< s N) (loop (+ s 1) (- E (-energy/J-plus s)))) (#t E)))) (define (energy grid) (* J (energy/J grid))) (define (time-step) (let loop ((n 0)) (cond ((< n N) (single-spin-flip! GRID) (loop (+ n 1)))))) (define (display-params . p) (let loop ((p p)) (cond ((not (null? p)) (display (car p))(display ": ")(display (cadr p)) (cond ((not (null? (cddr p))) ; not last elt? (display ", ") (loop (cddr p))))))) (newline)) (define (display-config) (display-params "D" D "N" N "L" L "BETA*J" (BETA*J) "RANDOM-STATE" (random-source-state-ref default-random-source))) (define TIMES #f) (define (main args) (random-source-pseudo-randomize! default-random-source 0 0) ; (write args)(newline) (set! TIMES args) (display-config) ; (display-spatial-sample GRID) (let loop ((t 0)) (cond ((< t TIMES) (time-step) (loop (+ t 1))))) (display-params "E" (energy GRID) "M" (magnetization GRID)) (display-spatial-sample GRID) )

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Re: [gambit-list] optimizing computer simulations of the Ising model
by olaf.rogalsky＠web.de 26 Fév '09

26 Fév '09

Depending on what you are trying to do, great speed improvements can be achieved by "entropic sampling"/"importance sampling", where mircocanonical phase states are visited with a propability, which is inverse proportional to the density of states. There is a large literature on this topic, for example: http://en.wikipedia.org/wiki/Importance_sampling http://www.cms.tuwien.ac.at/media/pdf/publications/PRE_71_066705_2005.pdf http://hrma.physics.sjtu.edu.cn/SimulationPhysics/PRL02050.pdf Olaf -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

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copy-file on windows & links
by Christoph Bauer 25 Fév '09

25 Fév '09

Hi, I have a question concerning copy-file on windows. my setup: filesystem on linux mounted over samba on windows I try to copy a file with "copy-file", which is acutaly a symlic link under linux. This results in a .lnk-file. Is there a way to make a real copy of the file? Thanks for help, Christoph Bauer

1 0