The NumWorks graphing calculator

September 28, 2017

This article was contributed by Tom Yates

As the Internet of Things (IoT) becomes ever more populous, there is no shortage of people warning us that the continual infusion into our lives of hard-to-patch proprietary devices running hard-to-maintain proprietary code is a bit of a problem. It is an act of faith for some, myself included, that open devices running free software (whether IoT devices or not) are easier to maintain than proprietary, closed ones. So it's always of interest when freedom (or something close to it) makes its way into a class of devices that were not previously so blessed.

In this case, the device is the humble scientific calculator. Many people now use their smartphones when they need to do sums, but others still find a calculator a useful thing to have at hand. Recently, NumWorks, a new scientific graphing calculator with an open-design ethos was released. Although it is far from fully free at this point, it is a major step forward from the user-hostile position most calculator manufacturers have taken, and it is interesting to see to what extent it fulfills its promise.

NumWorks was founded about two years ago. Romain Goyet, the CEO, comes from a software engineering background. He was looking to start his next company when he wandered into a supermarket and saw his old college calculator on the shelf — unimproved in over a decade and more expensive than it used to be. Recalling how he'd had to spend hours poring over a manual to persuade his old calculator to do anything useful, and perceiving calculators in general to be user-hostile, unintuitive, and stuck in a rut, he decided to make a calculator that was easier to use and, crucially, easier to improve. The NumWorks device (currently the N100) and Epsilon, the OS that the N100 runs, are the result.

My current calculator, the device against which I'm judging the NumWorks, is a TI-84 Plus. As an industrial product, the NumWorks compares well. It's about the same width, an inch shorter, about half the thickness and slightly over half the mass of the TI and, at €80 or $100, competitively priced. The NumWorks's screen is much better than the TI's, offering color, a lot more pixels (320x240 versus 96x64), and backlighting. The general design feel is much more video game than brick, though the gold-on-white print used for the alphabet functions on the keys is almost illegible in poor light (Goyet says NumWorks may darken the ink used, but that it wanted to avoid labels relating to advanced features crowding out the basic function set). π, the exponent function (x10^x), and Ans (which recalls the result of the previous calculation) are all on unshifted keys, which does make the workflow simpler than the TI's.

It's a pretty intuitive device to use. Basic arithmetical operations are all on the main keys. Less basic operations (trigonometric functions, exponentials, and complex numbers) are on the smaller keys above. Sophisticated operations (integrals, sums and products, permutations and combinations, and the like) are accessed through the "toolbox" key, which I took to be a print key for some hours. Other modes (such as graphing and linear regression) are accessed via the high-level navigation controls at the top of the keypad. I was able to get up and running with graphs within two hours, something I still can't do reliably on my TI-84 Plus after two years. That said, it's really handy that the NumWorks is so intuitive, because the online manual is so short as to be virtually useless.

On the openness front, the device does fairly well. The STL files that describe the calculator's plastic parts are all available on GitHub, as is the Epsilon operating system. Epsilon is flashed onto the device via the USB Device Firmware Upgrade protocol, which is a well-established and well-supported method of flashing new OSes.

That said, all of the GitHub content is available only under Creative Commons (CC) Attribution-NonCommercial-NoDerivatives (BY-NC-ND), a license even more restrictive than CC Attribution-NonCommercial (BY-NC, which itself is not regarded as free). Asked about this, Goyet ascribes the choice of license to NumWorks's fear of clone manufacturers undercutting it, but recognizes that the license is a disincentive for both contributors and enthusiasts. It requires a CLA from contributors which requires a broad patent grant and permits relicensing; even if commercial considerations require NC for some time, the ND restriction is likely to be removed in the near future. Going to a CC BY-NC model would at least permit the community to continue to improve the device if the company were to fold or take a new direction. While I wish the device were fully free, it is worth contrasting how TI has tried to impede the user community's efforts to run custom software on their TI-84 Plus calculators; NumWorks does seem to be trying to be as free as it thinks it can be.

When it comes to mathematics, the NumWorks didn't come off so well. It supports complex numbers, but when I asked it to calculate Euler's identity it told me the answer was on the order of 10^-8i, instead of zero. Asked for the calculator standard of 69!, it told me the answer was infinite; experimentation revealed that the largest factorial it could manage was 34!, and that results over about 3.4x10³⁸ were out-of-range.

However, this was with the installed version of Epsilon, which for mine was 1.0.3; a look at the GitHub repository revealed that the current version was 1.1.2. The instructions for building the software are pretty simple; git clone downloads a copy, and repeated cycles of make clean && make (to find out what I was missing) and dnf whatprovides (or your distribution's equivalent to find out what package you need to provide a missing command, library, or cross-compiler) allowed me to compile my first new calculator OS in about half an hour. make app_flash turns out to require privilege under Fedora 26, but once I'd installed dfu-util and used sudo to become root I was prompted to connect the calculator via USB and press its (recessed) reset button. Doing so started the flashing, which completed in about 70 seconds, after which the calculator rebooted automatically and presented me with the new OS.

Version 1.1.2 did quite a lot better than its predecessor. Euler's identity evaluated to zero; 69! evaluated correctly, as (to my surprise) did 70! — the new OS copes with numbers considerably larger than 10¹⁰⁰. Integration still had problems; asked to integrate the normal distribution function from -5 to +5, it incorrectly told me the result was undefined. After I logged this as a bug, a community member had diagnosed the underlying problem within a day, and provided a patch within another day. The patch has since been pulled, and I've downloaded, built, and flashed the new OS. Not only does the integral now evaluate correctly, but it does so in a time too short for me to measure; my TI-84 Plus takes over three seconds. For those who like some programmability in their calculators, a pre-release, restricted-functionality version of Python is now provided, though code entry on the NumWorks's keyboard is fairly painful, and only one program can be stored.

There are other issues: when answers are carried forward to new calculations, no more numerical accuracy is retained than is displayed on the screen, so taking the square root of 2 then squaring the result yields 2.000001. There are a number of other small grumbles I could mention, but the response to my first bug has been sufficiently positive that I'm prepared to assume that they'll get fixed in the fullness of time. There are also complaints about the Linux support; while Windows and macOS users can automatically flash the latest OS through their browsers, Linux users must compile and flash their own. Goyet is sympathetic to the idea that providing links to the binary images would let Linux users flash their NumWorks devices using dfu-util, without having to download all the tools needed to build their own images. It also would not require NumWorks to try to make the in-browser support work on all the browsers that people use on their many Linux distributions; so Linux support may get better soon. For readers who want to get up and running now, the toolchain isn't all that painful to assemble.

NumWorks itself seems open to feedback. To get to where it is, it has had to make some choices, such as the illegible color scheme and the odd license, but Goyet asserts that it's open to reviewing those choices in the face of community pressure. It has email, a reddit forum, and it seems to monitor the GitHub issue queues closely.

In summary, NumWorks is an elegant and promising device. I would certainly buy one for any sixth-form (i.e., high school) student or undergraduate of my acquaintance, though I'd make sure it was running the latest Epsilon before I gave it to them. I'd buy one for myself (in fact, I have). Yes, it has imperfections, but it also has mechanisms for dealing with them. Maybe it's a little more work than just buying a calculator from the supermarket, but let's face it, if we ask for our devices to be open so that we can understand and fix them ourselves, we perhaps should not be surprised when our relationship to them isn't that of consumer to product, but one of engineer to tool.

Index entries for this article
GuestArticles	Yates, Tom

to post comments

The NumWorks graphing calculator

Posted Sep 28, 2017 18:51 UTC (Thu) by davidstrauss (guest, #85867) [Link] (5 responses)

I have to say: I'm disappointed that it's not relying on a more established system like GNU Octave or, better, one with symbolic processing. Precise number storage can only go so far to getting perfect results for situations where you take a square root and then square the result. Symbolic processing can yield the correct result more reliably.

The NumWorks graphing calculator

Posted Sep 28, 2017 19:39 UTC (Thu) by jmspeex (guest, #51639) [Link] (4 responses)

Note that in octave, sqrt(2)^2-2 gives me 4.4409e-16, which is 2^-51

The NumWorks graphing calculator

Posted Sep 29, 2017 8:52 UTC (Fri) by davidstrauss (guest, #85867) [Link] (1 responses)

I'm not suggesting that Octave is perfect, just that it would be nicer to handle issues like this within Octave. Comparatively few people will benefit from fixing the code behind this calculator.

The NumWorks graphing calculator

Posted Sep 29, 2017 9:38 UTC (Fri) by njd27 (subscriber, #5770) [Link]

I presume that basing the calculator software on GPL code wouldn't have suited their licensing goals.

The NumWorks graphing calculator

Posted Sep 30, 2017 7:08 UTC (Sat) by madhatter (subscriber, #4665) [Link] (1 responses)

For clarification, I should add that the issue is solely with the accuracy of the carried-forward Ans token, representing the answer to an earlier calculation, since that's only evaluated to 7 sig fig. The internal accuracy of the NumWorks is far higher: arcsin(arccos(arctan(tan(cos(sin(9)))))) returns 9 (in degrees mode), as it should: even my TI84+ returns 8.99999997.

That said, (sqrt(2))²-2 also returns 4.440892x10^-16, while the TI84+ returns 0.

The NumWorks graphing calculator

Posted Oct 2, 2017 16:31 UTC (Mon) by davidstrauss (guest, #85867) [Link]

My point is that, for any given level of accuracy/precision, there's arithmetic you can feed it that will reveal its deficiencies. If the goal is to cleanly have the "square" and "square root" operations neutralize each other, that requires symbolic processing to be reliable. Otherwise, it's just a question of how far you can stretch the implementation before it breaks, and non-symbolic systems tend to break that way silently. Such systems yield results that are very close to the proper one but with bewildering notation (like the ones in the article).

The NumWorks graphing calculator

Posted Sep 28, 2017 20:10 UTC (Thu) by Lionel_Debroux (subscriber, #30014) [Link] (9 responses)

A €80 / $100 calculator with a full-featured CAS engine would indeed blast similarly priced, CAS-less models from the established calculator manufacturers cartel - for instance, the TI-84+CE and TI-83 Premium CE, which are the newest derivatives (the hardware is basically the same, the software differs) of the old 84+, and fare much better than the 84+ in a comparison against the N100.

However, the pristine NumWorks N100 can't be that calculator: 1 MB of Flash, i.e. only half of what e.g. the '1998 TI-89 provides (but accessible at a much faster rate), simply isn't enough to hold a full-featured CAS engine in addition to the other features expected from a graphing calculator, and 256 KB of RAM isn't much either.
Bernard Parisse made an experimental port of his Giac to the NumWorks simulator, which implements no binary size limit on x86/x86_64; according to him, the ARM binary would be much larger than the N100's Flash memory. The discussion in French is at https://ti-pla.net/t20445 (disclaimer: I'm a founding member and still staff member of TI-Planet, but there's no English-speaking reference about NumWorks+Giac at the time of this writing, I explicitly asked him in another thread).

The NumWorks graphing calculator

Posted Sep 29, 2017 0:17 UTC (Fri) by daney (guest, #24551) [Link] (2 responses)

I think a big reason that "the established calculator manufacturers cartel" is so effective is that The College Board (proprietors of SAT college entrance exams and AP curriculum) as well as ACT (another college entrance exam) only seem to all TI products to be used. Because of this, most US high school students effectively have no choice when it comes to calculator purchases.

CAS or no CAS, unless students are permitted to use the device, I don't think it will be commercially successful.

The NumWorks graphing calculator

Posted Sep 29, 2017 0:23 UTC (Fri) by daney (guest, #24551) [Link] (1 responses)

OK, so I just looked at the NumWorks web site. I guess they are cognizant of the need to get the thing ACT and AP/SAT approved. They claim that you can use it on the ACT, which is a good start.

I wonder though, with the ability to load custom firmware, if it can be certifiable for these tests, as you could in theory add functions to gain an advantage over others who would have only standard firmware.

The NumWorks graphing calculator

Posted Sep 29, 2017 14:10 UTC (Fri) by cpitrat (subscriber, #116459) [Link]

You can load any program on a TI. Back in my days, people were (uselessly) copying their notes in the calculator hoping it would help them. What could you possibly do in a firmware that you can't do in a program and that would bring you some 'advantage' ?!

The NumWorks graphing calculator

Posted Sep 29, 2017 1:16 UTC (Fri) by pizza (subscriber, #46) [Link] (3 responses)

FWIW, the STM32F412 part in the NumWorks is mid-range; that particular line tops out at 1.5M flash and 320K RAM, but the higher-end F469 (which may or may not be available in a compatible package) has 2M flash and 384K RAM.

They also support external DRAM and Flash, but that could require a bit of SW rework (ie "modules" paged into RAM) and probably hurt performance a bit. Not to mention cost more.

Anyway. I _really_ want to see this MathWorks endeavour succeed.

The NumWorks graphing calculator

Posted Sep 30, 2017 12:20 UTC (Sat) by joib (subscriber, #8541) [Link] (2 responses)

Mathworks? The company behind Matlab? They are somehow behind this?

The NumWorks graphing calculator

Posted Oct 1, 2017 8:11 UTC (Sun) by Lionel_Debroux (subscriber, #30014) [Link] (1 responses)

Although MathWorks does have at least an office in France (or did until recently ?), this "MathWorks" occurrence might have been a thinko.

The NumWorks graphing calculator

Posted Oct 6, 2017 12:02 UTC (Fri) by xav (guest, #18536) [Link]

They still do, a few blocks from here. And they're alive and kicking (employing some friends of mine).

The NumWorks graphing calculator

Posted Sep 29, 2017 13:53 UTC (Fri) by epithumia (subscriber, #23370) [Link] (1 responses)

My problem with this is that at the current pricing it is far closer to something like an HP Prime, which by many measures is a vastly superior calculator. Perhaps the design isn't as pretty or intuitive as the NumWorks but it does have a touch screen. The fact that it has RPN (and thus I can actually use it as a calculator) is a big deal for me but probably not important for most people.

It's true that TI is just exploitative, especially when they price the various editions of TI84 which are explicitly required by certain textbooks at nearly double the price of their highest-end NSpire calculators. (Though even then they charge extra for an NSpire with a CAS.) To displace them from that market (at least the local market with which I am familiar) you would have to provide something amazing at an even more amazing price. Doing simply "a whole lot better" at a slightly lower price just isn't enough, it seems, because TI keeps getting business.

HP gives a free emulator and smartphone application which exactly duplicate the Prime so students can just use their phone most of the time and only use the physical calculator in the classroom setting. They have a complete classroom connectivity solution (though it is unfortunately overpriced). It's simply not enough. You have to both cut costs and push hard against TI in innovative ways. Get these things out to schools as kits. Bundle them with 3D printers (on loan if necessary to keep the costs reasonable) so kids can actually make their calculators from parts. Get them involved and then let them keep the result, so that the learn the value of open design. And if you're going to try to do traditional sales, at least drop the cost by a third if not in half.

As an aside, I do wonder if Bernard Parisse is somehow involved in this effort. My understanding is that he is the author of GIAC and has done the CAS systems for HP calculators since the HP49.

The NumWorks graphing calculator

Posted Sep 29, 2017 15:12 UTC (Fri) by Lionel_Debroux (subscriber, #30014) [Link]

Your understanding is correct.

He made an unofficial mod of the computer version of the NumWorks software, which features Giac integration; at the same time, he started putting some Python compatibility syntactic sugar into Giac. You can see a couple screenshots of NumWorks+Giac in the forum topic where I posted a link to :)
Apart from the HP Prime running an official mod of Giac, the TI-Nspire series has enjoyed his unofficial port of Giac since 2014, named Khicas (good pun, definitely intended), whose binaries are upgraded on a regular basis to follow Giac enhancements.

The NumWorks graphing calculator

Posted Sep 29, 2017 6:22 UTC (Fri) by aleXXX (subscriber, #2742) [Link]

If it managed to calculate only up to 34!, it looks like it was using floats, and maybe they simply changed to double ?

I really liked my TI-68. It didn't do graphs, but it was so easy to calculate with complex numbers etc. Unfortunately the display stopped to work last year. :-/

The NumWorks graphing calculator

Posted Sep 29, 2017 6:53 UTC (Fri) by sytoka (guest, #38525) [Link] (20 responses)

The french law said that the calculator must have an exam mode (for the baccalaureate). Every Student in hight school had to change for this kind of calculator.

The NumWorks graphing calculator

Posted Sep 29, 2017 7:20 UTC (Fri) by madhatter (subscriber, #4665) [Link] (16 responses)

Yes, the NumWorks has such a mode, which clears the memory of all stored programs and data, flashes a red LED on the top of the unit, and requires USB power to leave the mode. I didn't dwell on it in the article because it's somewhat weird to anyone who doesn't have that law (ie, isn't French), but the NumWorks has it.

The NumWorks graphing calculator

Posted Sep 29, 2017 7:42 UTC (Fri) by Lionel_Debroux (subscriber, #30014) [Link] (15 responses)

Sadly, the PTT disease, which reinforces unequal treatment of citizens (to summarize, no more pre-existing user programs accessible during standardized tests => no way to slightly counter-balance the narrower feature set of cheaper models => yet another way poorer people are at a disadvantage against richer people), has been imported from other countries - but yeah, it's weird and counter-productive all the same :(

The NumWorks graphing calculator

Posted Sep 29, 2017 9:04 UTC (Fri) by anselm (subscriber, #2796) [Link] (14 responses)

In my school, shoes with track spikes were absolutely no problem for the PE tests, but programmable calculators in mathematics exams were right out. It was apparently OK if you could afford giving yourself an edge in sports, but not in maths.

The NumWorks graphing calculator

Posted Sep 29, 2017 10:29 UTC (Fri) by gdt (subscriber, #6284) [Link] (9 responses)

The problem being that modern calculators are so good that allowing them in secondary school exams would turn them into simple copying from the screen to the exam paper. To see an example, enter a polynominal into Wolfram Alpha, it will graph it, show the roots, and even show line-by-line working for obtaining the roots using all the different methods. So the examination bodies have choosen to restrict calculators to have little capability beyond what is possible with pen, paper and tables of functions.

There is a deeper question here, which is why in the presence of such computing power we persist in teaching mathematics as if that tool is not available. A way which is now very different to the way professional mathematicians, statisticians and engineers approach the same tasks. I was watching my daughter be taught graph theory and surprised that it didn't end with an introduction to a library like Python's NetworkX, which would have considerably helped them with their task of computing a 50 vertice graph. Similarly that the statistics topic didn't introduce R. There are obvious answers of course, and they are so difficult to overcome that it's clear how we got to this point. It's less clear how to get out beyond this point and towards a better mathematics experience for students.

The NumWorks graphing calculator

Posted Sep 29, 2017 12:18 UTC (Fri) by aleXXX (subscriber, #2742) [Link] (4 responses)

Learning and understanding how to compute the roots of an polynomial or how to solve a (small) linear equation system manually yourself is a good thing.
Without doing it manually on paper you don't understand how it works, and it trains your brain.

I know this may sound old...
I still think that one of the best lectures I had (20 years ago) was one where the professor explained the stuff by drawing it on a blackboard. IMO the best way to make somebody understand a problem is a person writing/drawing and explaining and pointing at the same time. Works without any computer.

The NumWorks graphing calculator

Posted Sep 29, 2017 15:07 UTC (Fri) by gutschke (subscriber, #27910) [Link] (3 responses)

That's why it often makes sense to administer those type of tests without allowing any calculators.

There are a good number of numerical problems that can be computed without the help of calculators.

And once the student has mastered the mechanics of math, you can let them take future tests "open book" and with a calculator.

Of course, those tests will be much more difficult

The NumWorks graphing calculator

Posted Oct 12, 2017 15:08 UTC (Thu) by Wol (subscriber, #4433) [Link] (2 responses)

One only has to ask why do modern students make blunders with orders of magnitude. Someone who's learnt maths the hard way (ie long multiplication etc), on being presented with a sum like "3 times thirty", will *know* the answer is approximately 100.

Somebody who's been taught to just enter it into a calculator will quite happily accept an answer that is approximately 10, or approximately 1000.

I regularly do a "sloppy calculation" in my head when using a calculator, precisely to pick up "finger trouble" errors, and it regularly saves my bacon ... :-)

Cheers,
Wol

The NumWorks graphing calculator

Posted Oct 12, 2017 16:34 UTC (Thu) by gutschke (subscriber, #27910) [Link]

I think I was in sixth grade, when I memorized log10(2) and log10(3). Turns out, that means with a second or two to think about it, I know the logarithms of all the numbers from 1 through 10. Although, admittedly, log10(5) and log10(7) are trickier and I'd have to interpolate.

There are an amazing number of problems that can be approximated, if you know these logarithms. You can usually get the order of magnitude and sometimes one or two significant digits. That's absolutely good enough to eyeball the results for plausibility.

Also, like most of you, I know the powers of two up to at least 16 -- and probably higher, if I give it a little thought. Turns out, a lot of problems that look difficult in base 10 look really easy in base 2.

Math is all about reducing a complicated problem to a different problem that is easy. And if you memorize a small number of constants from different problem domains, then your toolbox grows exponentially more powerful. Logarithms are particularly good for this, but some of the trigonometric functions are pretty useful, too.

I distinctly remember moments in university (back, when I still needed to do lots of math), when I would arrive at an approximate answer within seconds, whereas my peers took about one minute to get the exact answer from their calculators. Turns out, my answers were always within less than 10% of theirs, and often better -- which frequently is good enough.

The NumWorks graphing calculator

Posted Oct 14, 2017 7:22 UTC (Sat) by micka (subscriber, #38720) [Link]

I can testify that children taught operations by hand will absolutely have as much problems with decimal orders of magnitude as those taught using calculators. Order of magnitude (well... Sense based validation of results) is a different and mostly independent, unrelated, teaching. They can be quite conflated.
Take for example decimal comma positioning in manual multiplication. It will be placed by a calculus on operand comma position, not on estimated expected order of magnitude of the result. And learners will stick with it.

The NumWorks graphing calculator

Posted Sep 29, 2017 13:13 UTC (Fri) by mjthayer (guest, #39183) [Link] (1 responses)

I have been wondering about some sort of Raspberry Pi-based calculator - a Pi Zero with a suitable case and touch screen would be great for the purpose. If the SD card were easily accessible, examiners could provide their own ready prepared ones and would know exactly what students had. A little effort for the examiners of course, but why not.

The NumWorks graphing calculator

Posted Sep 29, 2017 14:15 UTC (Fri) by cpitrat (subscriber, #116459) [Link]

A constraint that calculators have is that you expect its 4 AA batteries to last longer than the calculator itself. Hard to reach with a raspberry-pi ...

The NumWorks graphing calculator

Posted Sep 29, 2017 14:30 UTC (Fri) by tialaramex (subscriber, #21167) [Link]

Aha! I think I can answer this one

OK, so, ultimately the goal is for the student to learn stuff. We have exercises, tests, coursework, all that stuff _only_ in service of this goal. At the top end, everybody involved is aware that's what is going on, and if you propose to cheat the tests rather than learn the material they will stare at you like you just said you've got an idea how to defeat the safety limits and cut your own arms off with the wood saw. We do not much care that you are able to actually add 5 + 7 = 12‡, our goal in asking that is only to verify that you properly understood what's going on there so that when we later assume that knowledge you're not left staring blankly into space.

‡ Although it will help in some jobs to not need a calculator or other machine to do this sort of simple arithmetic that's not why we're teaching it to children in 2017.

But at high school level this idea about cheating being _futile_ is not going to be something we can expect most of the students to understand. So rather than replace 100 hours of her classes with material about "This is why you probably ought to pay attention and not cheat in tests" we just go out of our way to not let your daughter cheat until much later, by which time hopefully she'll have figured this out for herself.

The NumWorks graphing calculator

Posted Sep 29, 2017 22:28 UTC (Fri) by anselm (subscriber, #2796) [Link]

The problem being that modern calculators are so good that allowing them in secondary school exams would turn them into simple copying from the screen to the exam paper.

I probably should have mentioned that that was in the 1980s. Calculators (programmable or not) used to be a lot more primitive then.

The NumWorks graphing calculator

Posted Oct 5, 2017 3:54 UTC (Thu) by Matt_G (subscriber, #112824) [Link]

When I was in high school I took the advanced stream of mathematics we were given the option (via a mail order form - this was back in the 90's) to order a TI graphical calculator at a discounted 'student price' my parents grumbled about the price a little and then allowed me to purchase it. I used it all through high school it was handy but I don't think anything spectacular nor did it give me any edge over students who opted not to order one. I can remember programming pong on it using the built in basic language (following instructions I found online) so maybe it did help me get into programming.

At university I found out about 10 minutes before my first exam all forms of programmable calculators were banned from examinations I rushed off and bought a cheap $10 Casio scientific calculator and (barely) made it back in time for the start of the exam. I used that Casio for the entirety of my Engineering degree - still have it. No idea what happened to my Graphical calculator.

The NumWorks graphing calculator

Posted Oct 9, 2017 15:45 UTC (Mon) by giraffedata (guest, #1954) [Link] (2 responses)

In my school, shoes with track spikes were absolutely no problem for the PE tests,

What were your PE tests like? Were you graded on how fast you ran?

The NumWorks graphing calculator

Posted Oct 15, 2017 22:10 UTC (Sun) by anselm (subscriber, #2796) [Link] (1 responses)

Were you graded on how fast you ran?

Basically yes. There was an official table from the state education ministry that converted timings into grades. To add insult to injury, the official table was blatantly sexist – for example, for some track lengths the same time meant a dismal grade for a male student but an excellent grade for a female student, even though for the distances in question the respective world-class times for men and women are very close together.

The NumWorks graphing calculator

Posted Oct 16, 2017 13:11 UTC (Mon) by mathstuf (subscriber, #69389) [Link]

Your PE class consisted of world-class runners? Anyways, while the best of the best may be close, it does not imply that their respective bell curves align. Or were the goal times very disparate for the distance?

Anyways, that sounds odd. I feel that we'd do it more by effort in the US. I can walk a 12 minute mile, but others can't even run that (for various reasons). I do not deserve the same grade for slacking off if they're giving it their all to get the same time. There are benchmarks for special mention, but I believe those are set up at some percentile of times across the nation (per sex) and are more descriptive than prescriptive.

How did your grading system deal with handicaps such as crutches (temporary injuries), wheelchairs (for longer-term afflictions), and the like?

The NumWorks graphing calculator

Posted Sep 29, 2017 17:54 UTC (Fri) by Cyberax (✭ supporter ✭, #52523) [Link] (2 responses)

I still don't understand why you even need a calculator for a math exam.

The NumWorks graphing calculator

Posted Sep 29, 2017 18:11 UTC (Fri) by gutschke (subscriber, #27910) [Link] (1 responses)

You only need it, if the instructor is too lazy to pick problems that can be solved with pencil and paper. It doesn't take much more effort. But it does take non-zero effort when designing the test.

And then of course, you could have a professor like the one I had in my first year in university. For some inscrutable reason, he thought it was a good idea to give 20% of the test score to anybody who successfully computed the value of a 4×4 determinant. I still don't follow his thinking on that.

The NumWorks graphing calculator

Posted Oct 5, 2017 13:19 UTC (Thu) by droundy (guest, #4559) [Link]

I'm right there with you on this. It's amazing how long my 3rd year university physics majors take to solve for the eigenvalues and eigenvectors of a diagonal matrix using pen and paper *after* having taken linear algebra. Many don't know the solution to an equation like 3a = a. These kinds of problems shouldn't require a calculator, but if you don't require students to think, why would you expect them to do so?

The NumWorks graphing calculator

Posted Sep 29, 2017 15:33 UTC (Fri) by david.a.wheeler (subscriber, #72896) [Link] (2 responses)

As an effort to be a commercial competitor, great, the world needs more competition.

But this doesn't seem to be related to open source software or freedom, and thus, not very relevant to lwn.net. Creative Commons (CC) Attribution-NonCommercial-NoDerivatives (BY-NC-ND) is just another proprietary license. Yes, it lets you see the source code, but since you can't make improvements or use it, you can't do much and there is little incentive to do so.

Just another proprietary calculator. Zzzzz. We already have those. It's not even very impressive as a calculator.

The NumWorks graphing calculator

Posted Sep 29, 2017 20:40 UTC (Fri) by zyga (subscriber, #81533) [Link] (1 responses)

Hey there. I'm just a FOSS developer and a user of the product in question. I'm not affiliated with numworks.

You *can* contribute to Numworks. They are active on github and are very receptive to patches. I hope to contribute a localization into Polish for other users, so that everyone can benefit from my (brief) work. I suspect they are still figuring out the licensing part but their behaviour is very much in the FOSS spirit.

The NumWorks graphing calculator

Posted Sep 30, 2017 15:08 UTC (Sat) by tialaramex (subscriber, #21167) [Link]

I think Free Software people are rightly wary of non-free software. So long as this system is CC-BY-NC-ND they can decide tomorrow that actually they'd rather you upgrade to their new device and cease all support for the old one. Any attempt by developers like yourself to keep it going would then be illegal, and it's up to them what they choose to do about that but it's unlikely to be comfortable for you. You might say you're sure the current leadership would never do that to you but (a) that's worth nothing in a court of law and (b) none of us is invulnerable to the effects of being hit by a bus, tomorrow this whole project could be owned by Casio or whatever.

If as the article hints they move to CC-BY-NC that's still not free, but it's a healthier situation in which to be volunteering your efforts because (so long as it remains a hobby) it can keep going without the say-so of the original creators.

About calculators in general

Posted Oct 5, 2017 5:43 UTC (Thu) by bjlucier (subscriber, #5281) [Link] (12 responses)

Once, when teaching introductory linear algebra, my students asked, of course, "Why do I have to learn this, my calculator can do it!"

This happened to be during the lecture on ill-posed systems, so I gave them a series of examples where there was no solution, multiple solutions, etc.

On each problem, the sole HP calculator in the classroom basically gave the right answer, and the TI calculators gave nonsense.

To which one of the TI-owning students exclaimed "It's not fair that he's allowed to use an HP calculator on the exam!"

Vel Kahan spent many years consulting for HP, from the very first HP calculator, helping them to get the right answers.

I hope that open-source calculators can replicate that success.

About calculators in general

Posted Oct 5, 2017 16:14 UTC (Thu) by smitty_one_each (subscriber, #28989) [Link] (10 responses)

Inviting the question: can this thing be configured for RPN? Otherwise, it's dead to me.

About calculators in general

Posted Oct 6, 2017 7:06 UTC (Fri) by madhatter (subscriber, #4665) [Link] (2 responses)

Traction getting be to seem not does but, for asked been has It: https://github.com/numworks/epsilon/issues/35

Excuse me; I meant it has been asked for, but does not seem to be getting traction (sorry, that was childish of me).

About calculators in general

Posted Oct 6, 2017 9:46 UTC (Fri) by smitty_one_each (subscriber, #28989) [Link]

I saw what you did there immediately.

About calculators in general

Posted Oct 6, 2017 15:25 UTC (Fri) by nybble41 (subscriber, #55106) [Link]

Did you mean:

> it asked-for has-been it traction getting seems not but

Just reversing the order of the terms does not change an infix expression to RPN. However, if you diagram the sentence and then write out the resulting tree in postfix order you should get something approximating "RPN English". (Complicated, of course, by implied/missing clauses, conjugation, and tenses. No doubt a specialist in English grammar could produce a more precise translation.)

About calculators in general

Posted Oct 6, 2017 7:44 UTC (Fri) by jem (subscriber, #24231) [Link] (6 responses)

Even if the firmware could be updated to support RPN, the keyboard doesn't look very usable for RPN entry. The HP Prime might be a better choice if you want RPN, or the HP 35s.

About RPN...

Posted Oct 9, 2017 9:25 UTC (Mon) by Herve5 (guest, #115399) [Link] (5 responses)

Or, alas, just RPN Calculator on Android, which besides not having real keys is otherwise close to perfect.

If NumWorks did propose an RPN version (with associated keys) I would buy it immediately indeed...

Android RPN Calculator

Posted Oct 9, 2017 13:44 UTC (Mon) by rschroev (subscriber, #4164) [Link] (4 responses)

There are at least two apps in the Play Store by that name, and a boatload of apps with similar names. I'd like to see if I can get used to RPN; which app would you recommend?

Android RPN Calculator

Posted Oct 9, 2017 13:48 UTC (Mon) by corbet (editor, #1) [Link] (2 responses)

I have "RpnCalc" by Edward Falk. It's not like having my old HP 41C back, but it is a good emulation of the RPN calculator experience. I'd recommend it.

Android RPN Calculator

Posted Oct 9, 2017 14:08 UTC (Mon) by rschroev (subscriber, #4164) [Link]

Thanks, I'll give it a try

Android RPN Calculator

Posted Oct 10, 2017 8:59 UTC (Tue) by Herve5 (guest, #115399) [Link]

same for me...

Android RPN Calculator

Posted Oct 10, 2017 9:46 UTC (Tue) by jem (subscriber, #24231) [Link]

One alternative is Free42, which emulates an HP-42. Then there's an app version of the HP Prime, which was mentioned earlier.

About calculators in general - HP vs. TI

Posted Oct 8, 2017 13:17 UTC (Sun) by pr1268 (guest, #24648) [Link]

Interesting anecdote about the lone HP user in a sea of TI calculators... That being said, I feel a need to vent a little frustration with my new (less than 2 year-old) HP 50g:

My TI-89 Titanium's display gave up after 10 years, so I got the '50g from Amazon.com at a "fire sale" price (about $70 USD packaged with a 2GB SD card); I'm unsure why it's so expensive now.

Despite lacking RPN (which I prefer), the '89 was a superior calculator, IMO. For example:

The '89 has the Π (product) function. I have yet to find this on the '50g.
Whereas Mr. Yates' TI-84 took "over three seconds" to integrate the normal distribution for -5 to 5, my shiny new '50g takes 13 seconds to (numerically) evaluate the same. At least Mr. Yates' experience with the patched NumWorks device sounds promising.
The '89 correctly evaluated the infinite sum of 2^-2n from 1 to ∞ as 1/3, but the 50g gives "1/(e^2*ln(2)-1)" (also correct but unintuitive). I have to do LNCOLLECT (through a menu) just to get "1/(2²-1)" and then EVAL to (finally) get 1/3.
Supporting both algebraic and RPN entry totally complicates the '50g's manuals (three large PDF's totaling 1765 pages!).

In summary, I'm unimpressed with the HP 50g. I thought that HP made calculators (graphing or not) superior to all other brands, but not this time.

Still, I'm intrigued by Mr. Goyet's product. Good luck to him and his company. And thanks to Mr. Yates for this article.