I can perhaps offer some help designing the interface, but I'm having way more fun at programming myself than mentoring. Which is a convoluted way to say I'm too busy and would decline (at this time) mentoring any such project. If someone else was mentoring and needed a sounding board for discussion, I'd have good resonance, though :) -- Hervé Brönnimann hervebronnimann@mac.com On Jun 4, 2008, at 12:04 PM, Paul A Bristow wrote:
Perhaps we can suggest it for GSoC next year? I'll try to remember to do that - but your supervision/mentoring will be invaluable.
I vaguely recall that an unlimited precision integer would be needed? Or was it just a big/whopper integer? This would be valuable as a Boost thingy anyway?
Paul
--- Paul A Bristow Prizet Farmhouse, Kendal, Cumbria UK LA8 8AB +44 1539561830 & SMS, Mobile +44 7714 330204 & SMS pbristow@hetp.u-net.com
-----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Hervé Brönnimann Sent: 04 June 2008 06:12 To: boost@lists.boost.org Subject: Re: [boost] Rounding, Truncating Values
Paul: Most valuable indeed. Like a bullion of gold, because in practice they aren't much slower than the run-of-the-mill sscanf/ sprintf (a few extra cycles, except once in a while in spurious boundary cases where you need more than one or two extra binary digits). But the guaranteed round-trip, and extra precision, is well worth it. But who's got the time... <insert here great proselytization about boost, library code, reuse, etc.> :)
Oh, I remember fondly implementing Bellerophon in grad school (Clinger's original scanf). We had two weeks in Dave Hanson's systems programming class, 40% of the grade for the code working on the given examples, 40% for working on his test suite -- which he *didn't* give us access to, and 20% for the style/doc. In 13 weeks, we worked 13 problems (two weeks each, one week to research/read and discuss during the next class, overlapping with implementing the previous project). Projects ranged from various SIGPLAN/research recent or classical articles illustrating systems issues, e.g. this (floating point), impl. a context switcher for Solaris threads in assembler, impl. a symbolic tree manip for optimization (Dave gave us his lcc compiler, we only tweaked the optimizing module), some new/ improved graph algorithm for manipulating symbols in a linker's symbol table, a couple of hard optimization problems (with heuristics), incl. some speach audio data analysis, etc. You get the idea.
Dave's class was the best programming class I ever took, and one I hope to teach again myself someday. If any teacher/instructor is listening, this is a formula I most highly recommend. Keeps everyone honest, and teaches discipline like nothing else. (Lots of work for the teacher though; Dave had set up a black-box server wherein we could test our program, and output had to be *identical*, a la ACM Competition; grading was automatic by running private test suite and diff'ing the outputs.)
I got Bellerophon to work all right, it isn't that hard if you follow the math (not a small feat, though), but it requires meticulous implementation skills (and will beat it into you if you don't have it). Then begins the fun with infinities and nans... and for dessert: subnormal numbers.
Either one (both?) would be a great SoC project, by the way, if any student is listening, once you have the right interface. -- Hervé Brönnimann hervebronnimann@mac.com
On Jun 3, 2008, at 10:59 AM, Paul A Bristow wrote:
I've glanced at the Burger and Dybvig algorithms you quote, but they don't seem too simple to implement. If any one can get they to work, they would be most valuable.
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