April 2014 - Gambit-list - mailman.iro.umontreal.ca

Gambit versus Python+GMP: Timing for Chudnovskys' algorithm for pi
by Bradley Lucier 07 Apr '22

07 Apr '22

Bakul Shah wrote a particularly elegant Scheme program for Chudnovskys' algorithm for pi based on the Common Lisp program here: https://bitbucket.org/tarballs_are_good/numericl/src/5fe8fe7089f48ab1c8a388… Nick Craig-Wood wrote a Python program using the GMP multiprecision library that appears to use exactly the same algorithm here: http://www.craig-wood.com/nick/articles/pi-chudnovsky/ I modified both programs a bit and include them here. They time the calculation of $10^n$ digits of pi for $n=1,2,3,4,5,6,7$. The results are heine:~/programs/gambiteer/gambit> !py python pi_chudnovsky_bs_gmpy.py 31415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679 ('chudnovsky_gmpy_mpz_bs: digits', 10, 'time', 1.0967254638671875e-05) ('chudnovsky_gmpy_mpz_bs: digits', 100, 'time', 3.0040740966796875e-05) Last 5 digits 70679 OK ('chudnovsky_gmpy_mpz_bs: digits', 1000, 'time', 0.00025582313537597656) Last 5 digits 01989 OK ('chudnovsky_gmpy_mpz_bs: digits', 10000, 'time', 0.00386810302734375) Last 5 digits 75678 OK ('chudnovsky_gmpy_mpz_bs: digits', 100000, 'time', 0.0834801197052002) Last 5 digits 24646 OK ('chudnovsky_gmpy_mpz_bs: digits', 1000000, 'time', 1.655979871749878) Last 5 digits 58151 OK ('chudnovsky_gmpy_mpz_bs: digits', 10000000, 'time', 30.67442488670349) Last 5 digits 55897 OK heine:~/programs/gambiteer/gambit> gsi chud1.scm Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 10, CPU time: 0.. Last 5 digits 26535. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 100, CPU time: 0.. Last 5 digits 70679. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 1000, CPU time: .004. Last 5 digits 1989. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 10000, CPU time: .028. Last 5 digits 75678. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 100000, CPU time: .472. Last 5 digits 24646. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 1000000, CPU time: 6.448. Last 5 digits 58151. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 10000000, CPU time: 98.612. Last 5 digits 55897. So it appears that for this algorithm applied to large integers, GMP's bignum routines are about 3-4 times as fast as Gambit's bignum routines. Not so bad. For smaller bignums, GMP has a bigger advantage. The C program gmp-chudnovsky.c includes certain optimizations to this basic algorithm: http://gmplib.org/pi-with-gmp.html ftp://ftp.gmplib.org/pub/misc/gmp-chudnovsky.c On my machine, compiled with gcc -O3 -march=native -o gmp-chudnovsky gmp-chudnovsky.c -lgmp -lm the CPU times for 1,000,000 and 10,000,000 digits are 1.064 and 18.200 seconds, respectively. This is with a somewhat older machine model name : Intel(R) Core(TM)2 Quad CPU Q8200 @ 2.33GHz running Ubuntu 13.04 with heine:~/programs/gambiteer/gambit> gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.7.3-1ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --with-system-zlib --enable-objc-gc --with-cloog --enable-cloog-backend=ppl --disable-cloog-version-check --disable-ppl-version-check --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-1ubuntu1) heine:~/programs/gambiteer/gambit> gsi -v v4.6.9 20130607151908 x86_64-unknown-linux-gnu "./configure '--enable-single-host' '--enable-multiple-versions' '--enable-shared'" and the Ubuntu-provided GMP 5.0.5. (I'm sure the GMP folks have a better way to build GMP on my machine than the "generic" 64-bit version provided by Ubuntu.) Brad

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object->u8vector as tree shaker?
by Bradley Lucier 29 Mar '15

29 Mar '15

Marc: It's not quite clear to me what object->u8vector does with procedures. I was thinking that if it pulled in all the functions not in system libraries, then it could be used as a tree-shaker. This is only a vague thought, but I find its interesting. Brad

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Javascript Backend
by Bob Coleman 16 May '14

16 May '14

Greetings, I have been playing around with the javascript backend and have been impressed with it's capabilities. Interacting with other javascript libraries is not a problem, but I haven't found a way for other javascript code to call scheme defined functions. Is there a way to define functions to be called by javascript similar to c-lambda or c-define? Also, is it possible to access the value of the -target flag in scheme? I would like to define some functions differently based on whether the program is being built for the C or javascript backend. Thanks for your help. Bob

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Figuring out opaque:, and macros expanding to macros
by Álvaro Castro-Castilla 02 May '14

02 May '14

Hi! I've been figuring out all the attributes available with define-type in Gambit. Testing and thanks to: https://mercure.iro.umontreal.ca/pipermail/gambit-list/attachments/20090226… https://mercure.iro.umontreal.ca/pipermail/gambit-list/2004-December/000043… I could understand all but one: opaque. The ways to "learn" how things work with macros producing code is generally the trick (pp (lambda () (macro...)) 'asdf). But what about macros that produce macros? In that case you get an empty form with 'asdf, so no way to know what has been generated. That of course applies to define-type. There is no difference in generated code with opaque: keyword, so I assume that it only affects non-generative types. Can I see the generated code in such case? Reading Gambit's code in nonstd.scm doesn't clarify things either. Thank you!

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Guide to getting Gambit running on iOS
by Axis Sivitz 02 May '14

02 May '14

I just wrote up a guide to starting with Gambit on iOS. I’d love to improve it if anyone has suggestions. http://asivitz.com/posts/running_gambit_scheme_on_ios In the future I hope to write up posts on FFI, Android, and some game related things as well. Cheers, Axis

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Is the number of allocated bytes reported by time accurate?
by Bradley Lucier 24 Apr '14

24 Apr '14

Marc: I get > (time (##bignum.make 2 #f #f)) (time (##bignum.make 2 #f #f)) 0 ms real time 0 ms cpu time (0 user, 0 system) no collections 48 bytes allocated no minor faults no major faults 4344 > (time (cons a b)) (time (cons a b)) 0 ms real time 0 ms cpu time (0 user, 0 system) no collections 48 bytes allocated 1 minor fault no major faults on a 64-bit machine; I would expect each of them to allocate 24 bytes (two a-digits and a tag in the first one, two slots and a tag in the second). So, can you explain what's going on? Brad

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Gambit saving lives in India, Pakistan and Africa!
by Petersen, Chris 14 Apr '14

14 Apr '14

Hi fellow gambitters, Some of you may have heard of our use of Gambit-based mobile health applications for clinical trials in low income countries. We’d like to announce that our biggest project so far, Community Level Interventions for Pre-Eclampsia (CLIP) has now entered the pilot phase in India, Pakistan and Nigeria. The trial uses a gambit-based mobile diagnostic tool to identify pregnant women with a high risk of adverse events (such as a stroke or seizures) occurring due to pre-eclampsia, a disease that is responsible for about 75,000 women and 500,000 infants dying every year. Once completed a total of 40,000 pregnant women will be screened under the trial. Of these, several thousand are expected to develop pre-eclampsia, so there is a very real potential for saving lives. In fact, we are already hearing of women testing positive in the pilot, and being sent to hospital thanks to the diagnostics in the Gambit/LambdaNative application. For those interested, there is now an open access paper available that describes different aspects of the Gambit-based software: http://dx.doi.org/10.1109/JBHI.2014.2301156 While I’m at it, the devices currently used for this particular trial (low-cost locally sourced Android phones) come without sensors. However, we would like to use pulse oximeter sensors with the phones as this will make the decision support algorithms more powerful. The technology is here, and UBC has recently started hosting a funding drive to bring it out there to those who need it: http://thesensorproject.org Please take a look and spread the word if you want to help us save lives and see Scheme - and Gambit in particular - used where it matters most. Chris

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Fwd: [Haskell] Video chair at ICFP
by Robby Findler 13 Apr '14

13 Apr '14

Forwarded on behalf of Johan Jeuring. Robby ---------- Forwarded message ---------- From: Johan Jeuring <J.T.Jeuring(a)uu.nl> Date: Sun, Apr 13, 2014 at 2:11 PM Subject: [Haskell] Video chair at ICFP To: haskell-cafe(a)haskell.org, haskell(a)haskell.org Dear people, We are busy organising ICFP 2014, which will in Göteborg in Sweden from August 31 until September 6 2014. I am looking for a Video chair to organise the recording of the events on video. Tasks - prepare the video recording of the events: equipment (camera's, software, microphones?), required post-processing, ... - instruct student-volunteers in assisting the recording process - oversee the post-processing of the recordings, and the uploads Budget - we have some budget available for buying or renting equipment for the video recordings, or we can pay you for you bringing your own equipment - we will defray your costs for travelling to Göteborg, staying in Göteborg, and attending ICFP 2014 and affiliated events Please contact me if you are interested in this position/task, With kind regards, Johan Jeuring General chair for ICFP 2014 _______________________________________________ Haskell mailing list Haskell(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell

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CFP: Workshop on Generic Programming (WGP) 2014
by José Pedro Magalhães 12 Apr '14

12 Apr '14

Apologies for multiple postings. ====================================================================== CALL FOR PAPERS WGP 2014 10th ACM SIGPLAN Workshop on Generic Programming Gothenburg, Sweden Sunday, August 31, 2014 http://www.wgp-sigplan.org/2014 Co-located with the International Conference on Functional Programming (ICFP 2014) ====================================================================== Goals of the workshop --------------------- Generic programming is about making programs more adaptable by making them more general. Generic programs often embody non-traditional kinds of polymorphism; ordinary programs are obtained from them by suitably instantiating their parameters. In contrast with normal programs, the parameters of a generic program are often quite rich in structure; for example they may be other programs, types or type constructors, class hierarchies, or even programming paradigms. Generic programming techniques have always been of interest, both to practitioners and to theoreticians, and, for at least 20 years, generic programming techniques have been a specific focus of research in the functional and object-oriented programming communities. Generic programming has gradually spread to more and more mainstream languages, and today is widely used in industry. This workshop brings together leading researchers and practitioners in generic programming from around the world, and features papers capturing the state of the art in this important area. We welcome contributions on all aspects, theoretical as well as practical, of * generic programming, * programming with (C++) concepts, * meta-programming, * programming with type classes, * programming with modules, * programming with dependent types, * type systems for generic programming, * polytypic programming, * adaptive object-oriented programming, * component-based programming, * strategic programming, * aspect-oriented programming, * family polymorphism, * object-oriented generic programming, * implementation of generic programming languages, * static and dynamic analyses of generic programs, * and so on. Program Committee ----------------- José Pedro Magalhães (co-chair), University of Oxford Tiark Rompf (co-chair), Oracle Labs & EPFL Peter Achten, Radboud University Nijmegen Nada Amin, Ecole Polytechnique Fédérale de Lausanne (EPFL) Pierre-Évariste Dagand, INRIA Paris-Rocquencourt Fritz Henglein, University of Copenhagen Andrew Lumsdaine, Indiana University Miles Sabin, Underscore Consulting LLP, Chuusai Ltd. Alexander Slesarenko, Huawei Labs & Keldysh Institute of Applied Mathematics (KIAM) Anthony M. Sloane, Macquarie University Wouter Swierstra, Utrecht University Meng Wang, Chalmers University of Technology Proceedings and Copyright ------------------------- We plan to have formal proceedings, published by the ACM. Authors must transfer copyright to ACM upon acceptance (for government work, to the extent transferable), but retain various rights (http://www.acm.org/publications/policies/copyright_policy) Authors are encouraged to publish auxiliary material with their paper (source code, test data, etc.); they retain copyright of auxiliary material. Submission details ------------------ Deadline for submission: Sunday 2014-05-11 Notification of acceptance: Friday 2014-06-06 Final submission due: Wednesday 2014-06-18 Workshop: Sunday 2014-08-31 Submitted papers should fall into one of two categories: * Regular research papers (12 pages) * Short papers: case studies, tool demos, generic pearls (6 pages) Regular research papers are expected to present novel and interesting research results. Short papers need not present novel or fully polished results. Good candidates for short papers are those that report on interesting case studies of generic programming in open source or industry, present demos of generic programming tools or libraries, or discuss elegant and illustrative uses of generic programming ('pearls'). All submissions should be in portable document format (PDF), formatted using the ACM SIGPLAN style guidelines (two-column, 9pt). Regular research papers must not exceed 12 pages. Short papers must not exceed 6 pages. If applicable, papers should be marked with one of the labels 'case study, 'tool demo' or 'generic pearl' in the title at the time of submission. Papers should be submitted via EasyChair at https://www.easychair.org/conferences/?conf=wgp2014 Travel Support -------------- Student attendees with accepted papers can apply for a SIGPLAN PAC grant to help cover travel expenses. PAC also offers other support, such as for child-care expenses during the meeting or for travel costs for companions of SIGPLAN members with physical disabilities, as well as for travel from locations outside of North America and Europe. For details on the PAC program, see its web page (http://www.sigplan.org/PAC.htm) History of the Workshop on Generic Programming ---------------------------------------------- Earlier Workshops on Generic Programming have been held in * Boston, Massachusetts, US 2013 (affiliated with ICFP13), * Copenhagen, Denmark 2012 (affiliated with ICFP12), * Tokyo, Japan 2011 (affiliated with ICFP11), * Baltimore, Maryland, US 2010 (affiliated with ICFP10), * Edinburgh, UK 2009 (affiliated with ICFP09), * Victoria, BC, Canada 2008 (affiliated with ICFP), * Portland 2006 (affiliated with ICFP), * Ponte de Lima 2000 (affiliated with MPC), * Marstrand 1998 (affiliated with MPC). Furthermore, there were a few informal workshops * Utrecht 2005 (informal workshop), * Dagstuhl 2002 (IFIP WG2.1 Working Conference), * Nottingham 2001 (informal workshop). There were also (closely related) DGP workshops in Oxford (June 3-4 2004), and a Spring School on DGP in Nottingham (April 24-27 2006, which had a half-day workshop attached). WGP Steering Committee ---------------------- Shin-Cheng Mu (chair) Jaako Järvi Andres Löh Ronald Garcia Jacques Carette Jeremiah Willcock Tim Sheard Stephanie Weirich Tarmo Uustalu

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Asynchronous callbacks
by Francisco 06 Apr '14

06 Apr '14

Hi, I'm doing some tests using SDL2 (via Scheme Spheres bindings), and I'm having an issue related to multithreading. I want to generate audio procedurally, so what I need basically is access to an audio buffer that I can write on. SDL2 provides access to this buffer using a callback mechanism, which periodically invokes a provided function that is responsible for filling the buffer. This function is invoked in a separate thread of the main event loop. I implemented this callback function using c-define, but it eventually leads to a segmentation fault. I understand that this is not possible using a single VM (based on [1]), but I have recently seen some discussion regarding multiple VMs on a single process [2]. Is this functionality available for testing? I know that for the moment it is considered alpha, but it could help for doing some preliminary tests. I intend to have the main program running on a Gambit VM, and for audio processing implement a C callback which will in turn invoke a function on a different Gambit VM (both created when the program starts, probably on a simple C initialization program). These VMs would communicate via message passing/sockets/etc. For the moment I have the audio processing logic implemented in pure C, but I'd rather use Scheme for (almost) everything. This issue also arises in other asynchronous calls, for instance suspend/resume events on mobile platforms (Android specifically). I know that using multiple processes is an option on desktop versions, but I don't think I can create separate processes on Android. Thank you! Regards, Francisco [1]: https://mercure.iro.umontreal.ca/pipermail/gambit-list/2006-June/000741.html [2]: https://mercure.iro.umontreal.ca/pipermail/gambit-list/2014-February/007441…

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