Casio fx-991EX is very disappointing... - Page 1
Forum section: electronics / general

author: MBY
author_rank: Regular Contributor
timestamp: May 04, 2019, 11:07:05 pm
content: A few months back I purchased an Casio fx-991EX, mostly because it got good marks on this forum and it had a spreadsheet - something I could see the use for in a calculator.But it's all a sham! I did know that it was not a programmable calculator so I was prepared, even thou I don't think there are any excuses for not make a scientific calculator programmable these days. But the things the calculator are supposed to do, it doesn't do well. I have searched the PDF manual and the web for instructions how you save a spreadsheet, only to come to the concussion that you can't. You can't even retain a spreadsheet when exit to do another things. What the hell is the meaning of this?Another really dumb thing, and this one is an death sin - the prime factorization falsely report prime when the factors are > 1000. This is sooo dumb. I know exactly why and that makes it even dumber. The calculator obviously have a table with prime factors 2...997 and tries only to divide with those values. The calculator is really fast, so there is no reason not to use any wheel algorithm instead of a silly table (a table likely takes up a lotmoreof ROM than a proper algorithm) so it not falsely report composites (1009² for instance) as primes. Even if the manual mentions it, I regard that as defective.The aesthetics of the calculator is nice, and the build quality is okay, typical for modern Casios, but I find the symbols with "sqrt()" and / instead of sqrt(x) and x/y, etc, to be silly and confusing. It is also a bit sad to see that Casio has "imported" their silly menu system from their graphic line of calculators instead of mature away from it. Why does things like complex math and matrices be different "modes"? It is just silly!The display is nice, as told, but many functions feel more like gimmicks than the result of thoughtful consideration. It is like Casio tries to sell the damn thing with "the most functions" like digital cameras with "because of most megapixels" inhttps://xkcd.com/1014/. Why a spreadsheet that is completely useless and why a factorization function that cannot factorize? And, to no-ones surprise, the factorial function is not a gamma function, does only work with integers. Thats always the thing that separate the boys from the men. HP has done a proper gamma functions for decades and decades, but I have yet to see it work in any other calculator (perhaps TI-86? I have a memory of some non-HP calculator able to calc gamma for half-integers (eg. 5.5, etc)). The QR function? I don't know what it's for. The neoreader app on my phone doesn't seem to recognize it anyway. Separate on- and off-buttons? Irritating. A shifted "recall" button is irritating.Another stupid thing is the character table. The x10^x button yields a "x10^x" token instead of an "E", so numbers like 2.5*10^20 shows like "2.5x1020 instead of what has been the standard notation for ages and ages in computers and calculators, 2.5E20.As I said, the look and feel is good. Not HP-good of course, but it's a thin, lightweight calculator with a good hi-res display. I'm sure it has an excellent battery life. All Casios tend to have a very good battery life (again, not as good as some HPs, but better than most calculators, even some other HPs). It's a shame that it's not very user friendly and that a few of the selling points are just a scam.I know it has a few other non-features that irritates me, but I haven't used the thing for a couple of months now. Just found it again in a drawer and decided to play a little with it.

author: KL27x
author_rank: Super Contributor
timestamp: May 05, 2019, 08:50:31 pm
content: QuoteCell phones and computers? I don't want a programmable calculator.QuotePerhaps in someone else's line of work these features are useful despite their limitations?I've a 991, but I hardly ever touch it. The 115 is my main workhorse; it's simpler, and it covers all of my regular needs.

author: iMo
author_rank: Super Contributor
timestamp: May 05, 2019, 09:14:55 pm
content: These kinds of calculators are mainly targeted towards mainstream students. And today most schools require dumb calculators. Therefore the manufacturers follow that.People who want something special build their own gadgets - ie WP-34s, SwissMicro, special replacement chips for older HP-models, etc..For exampleHERE, few years back the guys built the most precise calculator ever (WP-34s, open source), it can do all the fancy math you would require with the best precision available. I built one for myself, it cost me $20.

author: MBY
author_rank: Regular Contributor
timestamp: May 05, 2019, 09:49:36 pm
content: Quote from: KL27x on May 05, 2019, 08:50:31 pmWell, suppose you found your dream calculator. It has exactly everything you need and nothing more, except, it happens to be programmable. What is the downside?I can understand the attitude "I don't program on calculators", but it is hard to understand "I don't want a programmable calculator".Quote from: KL27x on May 05, 2019, 08:50:31 pmWell, sure, but that doesn't make the functions non-broken. I mean, it has to be a design flaw or a bug. Continuous memory is not exactly high tech and Casio have excelled here for decades. And a prime table? Come on! You are doing it wrong, Casio. There is no excuse.Quote from: KL27x on May 05, 2019, 08:50:31 pmAgree. The fx-115 is a very neat pre-VPAM-nonsense calculator. But doesn't it have rudimentary programmability? Maybe I mix it up with fx-180?

author: MBY
author_rank: Regular Contributor
timestamp: May 05, 2019, 10:01:25 pm
content: Quote from: imo on May 05, 2019, 09:14:55 pmYep, I know. The "Classwiz" thing. But I did not expect the spreadsheet to be a dud and why add a factorization function if you cannot do it properly? The last thing is the thing I lost temper with. You cannot describe it as anything but faulty.And yes, I own two SwissMicros and a shitload of HPs from woodstocks to the poor HP-35s, my favorites being the HP-32sii, HP-15 and perhaps 48GX. I'm not out of calculators, I own a bunch of Casios as well, and the older, the better. I bought the fx-991ex because it got good marks from everywhere, but I'm now puzzled to understand why. It is like all other modern Casios, but with more broken "features", albeit having a new nice look. If they could make an update that allows you to exit and enter the spreadsheet and got rid of the faulty factorization gimmick it would be a very decent calculator. Except, it's a waste of general computing ability not to give access to that general computing ability.

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: May 05, 2019, 11:30:46 pm
content: Quote from: MBY on May 04, 2019, 11:07:05 pmCommodore SR9190Rthis guy:http://mycalcdb.free.fr/main.php?l=0&id=555Let me tell you about this Calculator, and its Gamma function. Back around 1977 I was a mathematically precocious teen-ager entering high school and they just began permitting the use of calculators in class. That is except for my chemistry teacher who mandated slide rules because he felt slide rules enhanced the students ability to estimate magnitudes as a form of error checking.Well my fascination with finding out how scientific calculators worked led me to research the CORDIC algorithm and also study analytic continuation. I feel like the Gamma function was the gateway drug to higher mathematics and I am probably not the only math autodidact to be triggered by it. I have very fond memories of that calculator and still have it somewhere, in pieces, in my stash. So it wasn't only HP calculators, but yes a Gamma function key is a rare thing.

author: MBY
author_rank: Regular Contributor
timestamp: May 06, 2019, 12:03:52 am
content: Quote from: chickenHeadKnob on May 05, 2019, 11:30:46 pmAhh, thank you! I own some old Commodore calculators, but only four bangers. I agree. The gamma function is a "gateway" to higher maths. As a young no-nothing, I discovered that you can do factorials with non-integers. Of course I got interested in how and why you can extend factorials to reals (and even complex). I trying to remember which of my calculators that do integers and half-integers, but not the real deal. Probably a Sharp graphing calc, but it's in a terrible shape so I can't confirm it.So Casio really should have a real gamma function. On their "educational" models.

author: KL27x
author_rank: Super Contributor
timestamp: May 07, 2019, 10:55:57 pm
content: QuoteIt might be programmable, but I wouldn't know.QuoteIf it had exactly what I needed with nothing more, then it wouldn't be programmable.I don't know that there's a big downside, but I wouldn't get any upside.

author: Tarloth
author_rank: Regular Contributor
timestamp: May 08, 2019, 11:46:29 am
content: I did buy few months ago for my son a HP39GII new (but old) from chinese surplus and it's a (not than) old beast for less money than most of casio or sharps with less power or specs. In the 90's I had an HP48 and before it a HP41 and still love RPN but new generations prefer algebraic input at school. Now I use cellphone calculators in the field and Wolfram maths for serious tasks when I work in my desk. Not take with me calculators anymore for me, but I recognize that I'm was tempting to buy two HP39 few months ago :-)

author: bd139
author_rank: Super Contributor
timestamp: May 08, 2019, 12:41:35 pm
content: You can turn off math entry mode on the 991EX. Works better thenOr buy an HP 35s