Author Topic: What calculator do you use ?  (Read 173316 times)

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jucole

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Re: What calculator do you use ?
« Reply #275 on: November 17, 2012, 01:17:35 pm »
I'd always loved my Sharp calc but it's been showing it's age recently; so when I saw this almost identical el-crapo for £5 in Tesco the other week, I just had to get it!! you can just smell the cheap plastic!! I love it!!

 

Offline IanB

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Re: What calculator do you use ?
« Reply #276 on: November 17, 2012, 07:28:47 pm »
I'd always loved my Sharp calc but it's been showing it's age recently; so when I saw this almost identical el-crapo for £5 in Tesco the other week, I just had to get it!! you can just smell the cheap plastic!! I love it!!

That looks so similar it's like it has to be using the same chip. Does it give the same numerical results?
 

jucole

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Re: What calculator do you use ?
« Reply #277 on: November 17, 2012, 09:48:29 pm »
I'd always loved my Sharp calc but it's been showing it's age recently; so when I saw this almost identical el-crapo for £5 in Tesco the other week, I just had to get it!! you can just smell the cheap plastic!! I love it!!

That looks so similar it's like it has to be using the same chip. Does it give the same numerical results?

Hi yes I believe the numerical results are the same; so like you say it's more than likely the same chip-set.

 

Offline larry42

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Re: What calculator do you use ?
« Reply #278 on: November 17, 2012, 10:04:12 pm »
HP48 emulator on HTC android phone. The original is too heavy/precious to take with me :)

Sent from my HTC One S using Tapatalk 2

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Offline Rick

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Re: What calculator do you use ?
« Reply #279 on: November 18, 2012, 12:48:49 am »
I'd always loved my Sharp calc but it's been showing it's age recently; so when I saw this almost identical el-crapo for £5 in Tesco the other week, I just had to get it!! you can just smell the cheap plastic!! I love it!!

I have been using almost the same Sharp since 1987! It is an EL512 with 4 extra programmable functions. It's beautiful with very very soft keys, something I did not have with my previous Texas Instruments brand calculators, they were horrible in this respect. I lost the 1st Sharp EL-512 in 1987 a few months after I bought it, then I bought a new identical one, a heavy burden on my student's budget then. Yesterday I have opened and cleaned the contacts under the keys, it is now as good as before.
« Last Edit: November 19, 2012, 12:19:14 am by Rick »
 

Offline T4P

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Re: What calculator do you use ?
« Reply #280 on: November 18, 2012, 05:56:13 am »
Being a student you will inevitably lose your calculator every now and then and run into shitty calculators because your budget is not that much ._.
I just use a Sharp EL-509WS (Worst contrast ever) that goes for roughly about 10$ ? For my exams, other times i use a plethora of calculator emulators on my phone
Mainly the Andie Graph with the TI-86 ROM inside as well as the Graph 89 Free with the 89 Ti ROM inside, oddly i never use the Droid48 because i do not know how to make use of RPN mainly but my favourite calculator is the TI-86!
 

Offline amyk

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Re: What calculator do you use ?
« Reply #281 on: November 18, 2012, 10:00:43 am »
I'd always loved my Sharp calc but it's been showing it's age recently; so when I saw this almost identical el-crapo for £5 in Tesco the other week, I just had to get it!! you can just smell the cheap plastic!! I love it!!

That looks so similar it's like it has to be using the same chip. Does it give the same numerical results?

Hi yes I believe the numerical results are the same; so like you say it's more than likely the same chip-set.
Did you test it with this?
http://www.rskey.org/~mwsebastian/miscprj/forensics.htm#algorithm

According to the result table:
http://www.rskey.org/~mwsebastian/miscprj/models.htm
The EL-506P used two different chipsets depending on the year.
 

jucole

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Re: What calculator do you use ?
« Reply #282 on: November 18, 2012, 11:02:53 am »
I'd always loved my Sharp calc but it's been showing it's age recently; so when I saw this almost identical el-crapo for £5 in Tesco the other week, I just had to get it!! you can just smell the cheap plastic!! I love it!!

That looks so similar it's like it has to be using the same chip. Does it give the same numerical results?

Hi yes I believe the numerical results are the same; so like you say it's more than likely the same chip-set.
Did you test it with this?
http://www.rskey.org/~mwsebastian/miscprj/forensics.htm#algorithm

According to the result table:
http://www.rskey.org/~mwsebastian/miscprj/models.htm
The EL-506P used two different chipsets depending on the year.

great site!    both calcs came out as 8.99999863704 so according the look-up "Sharp EL-506P (mid-80s, earlier version)" and the "Sharp SC6992" chip. So I cracked them open and took a pic. (left el-crapo, right is the sharp el-506p)


 

Offline quarks

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Re: What calculator do you use ?
« Reply #283 on: November 18, 2012, 09:01:10 pm »
That's interesting. Because I just worked with Excel2010 before I saw this. I tried it and was very surprised when
ARCSIN(ARCCOS(ARCTAN(TAN(COS(SIN(9))))))=0,42477796076938 showed up.
This seems to be the result with radians instead of degree angle. Does anyone know how to change this in excel.

Then I did the same test:  arcsin (arccos (arctan (tan (cos (sin (9) ) ) ) ) )
with my HP48GX, HP50g, HP48GX emulator on Android and Windows 7 64bit
result always was 8.99999864267 (as stated in the article).

greetings from Germany
 

Offline Fsck

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Re: What calculator do you use ?
« Reply #284 on: November 18, 2012, 09:13:57 pm »
TI nspire CX CAS - lost my ti-89 so this replaced it
ti-84 for easy arithmetic
matlab & Excel for numerical analysis
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Offline PA4TIM

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Re: What calculator do you use ?
« Reply #285 on: November 18, 2012, 09:35:09 pm »
I tried my 35, 35s, 15C, 15C app they all agreed with the table
Tried my 45 ipad app and 42S windowsPhone app and they do not agree.
The 45 gives 9.000000000
The 42S gives 9.0000000004
www.pa4tim.nl my collection measurement gear and experiments Also lots of info about network analyse
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Offline IanB

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Re: What calculator do you use ?
« Reply #286 on: November 18, 2012, 09:35:53 pm »
Evidently computers may have an advantage over calculators. This is what my calculator program produces:

> 180/pi * asin acos atan tan cos sin (9/180*pi)
9
> ans - 9
1.06581410364e-014
>

Perhaps calculators these days should simply be based on an ordinary micro and do IEEE double precision arithmetic in binary?
 

Offline IanB

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Re: What calculator do you use ?
« Reply #287 on: November 18, 2012, 09:52:39 pm »
Evidently computers may have an advantage over calculators. This is what my calculator program produces:

> 180/pi * asin acos atan tan cos sin (9/180*pi)
9
> ans - 9
1.06581410364e-014
>

Perhaps calculators these days should simply be based on an ordinary micro and do IEEE double precision arithmetic in binary?

OK, not quite the right test. My program doesn't have a degrees mode. Here is keeping everything in degrees:

> d=180/pi
57.2957795131
> r=pi/180
0.0174532925199
> d*asin(d*acos(d*atan(tan(r*cos(r*sin(r*9))))))
8.99999999983
>

Now the result is not quite so close. Maybe I need quadruple precision...
 

Offline PA0PBZ

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Re: What calculator do you use ?
« Reply #288 on: November 18, 2012, 10:14:50 pm »
The Windows 7 Calculator:

asind(acosd(atand(tand(cosd(sind(9)))))) - 9
3.3055861301806391104645128745734e-32


Close enough  8)
Keyboard error: Press F1 to continue.
 

Offline rr100

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Re: What calculator do you use ?
« Reply #289 on: November 19, 2012, 07:30:56 am »
Evidently computers may have an advantage over calculators. This is what my calculator program produces:

> 180/pi * asin acos atan tan cos sin (9/180*pi)
9
> ans - 9
1.06581410364e-014
>

14-16-20 digits (or even much more) precision is nothing, even 64kB RAM devices should to that easily.
This is what computers do:

Code: [Select]
> 180*arcsin(arccos(arctan(tan(cos(sin(9*Pi*(1/180)))))))/Pi;
                                       9

> arccos(arctan(tan(cos(sin(9*Pi*(1/180))))));
                                        Pi
                                   sin(----)
                                        20

That's a 9 of course.
With a (newish) Maple but I'm convinced even the V5 from 1997 would do the same.
 

Offline rr100

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Re: What calculator do you use ?
« Reply #290 on: November 19, 2012, 11:45:56 am »
In fact I was too quick with the example above, this is the one that does something closer to the "fingerprinting" test (before I put only the first and last conversion):

Code: [Select]
> 180/Pi*arcsin(180/Pi*arccos(180/Pi*arctan(tan(Pi/180*(cos(Pi/180*(sin(9*Pi/180))))))));
                                                                              9
> %-9;
                                                                              0
Of course the functions can be redefined to work in degrees directly but it's not worth it. Also some intermediary result (as in didn't type all conversions) from Maple:
Code: [Select]
> 180/Pi*arcsin(arccos(180/Pi*arctan(tan(Pi/180*(cos(Pi/180*(sin(9*Pi/180))))))));
                                                                                        Pi
                                                               180 arcsin(1/180 Pi sin(----))
                                                                                        20
                                                               ------------------------------
                                                                             Pi
 

Offline ciccio

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Re: What calculator do you use ?
« Reply #291 on: November 21, 2012, 06:14:49 pm »
That's interesting. Because I just worked with Excel2010 before I saw this. I tried it and was very surprised when
ARCSIN(ARCCOS(ARCTAN(TAN(COS(SIN(9))))))=0,42477796076938 showed up.
This seems to be the result with radians instead of degree angle. Does anyone know how to change this in excel.
I use EXCEL 2003, and for what I understand it works in radians, not in degrees.
There is a function that converts radians in degrees (GRADI in my Italian Excel) and another one to convert degrees in radians (RADIANTI).
I get lost with long formulas in Excel, so I prefer to put every single part of the formula in a separate cell.
The following image is a screeenshot of the formula, showing the great accuracy of the result.
Best regards
Strenua Nos Exercet Inertia
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I always invent new ones
 

Offline rr100

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Re: What calculator do you use ?
« Reply #292 on: November 21, 2012, 10:21:05 pm »
Technically to do the same as the pocket calculators you'll need to convert each function in between to radian operation, not only first and last one (easy trap, I went for it as well, see above).
Also it would be interesting to see what is I1-9 or even better (I1-9)*100000000 for example to see if anything hides behind 9.0000...

Open question: anyone knows some "pocket calculator" where you can set higher precision for this kind of operations? And I mean larger than the usual 8-20 digits, maybe 50-100, or even much more. This isn't a really challenging task in itself assuming you have reasonable RAM (and by that I mean even 1-2MB would be plenty), probably the hard part is the user interface itself.

And this can have (somehow) practical applications... for example: http://what-if.xkcd.com/20/
At some point the damn cat steps on the keyboard ... and we start with a speed of 0.9999999999999999999999951c (that is almost c, speed of light, max speed permitted in this universe). You just can't do 1-0.9999999999999999999999951^2 (for example) on any calculator I know of (or I don't know how). And you might need precisely this speed squared, it is something that comes up immediately in this context.
Of course you can do it on paper "old style" like you transform your number in something like (1-49/10^25) and then you do by hand (1-49/10^25)^2. But sometimes you have stuff that doesn't play that nice or you just want to do the calculation and get the result without any tricks.
So, is there any pocket calculator that can do 1-0.9999999999999999999999951^2 with some reasonable precision ?
 

Offline IanB

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Re: What calculator do you use ?
« Reply #293 on: November 21, 2012, 11:20:41 pm »
So, is there any pocket calculator that can do 1-0.9999999999999999999999951^2 with some reasonable precision?

Fortunately you don't need a calculator for this. You can do this one in your head (well OK, you might need a pencil and the back of an envelope).

First of all we need 0.9999999999999999999999951^2. A quick application of the binomial theorem tells us that the answer is 0.9999999999999999999999902 (we subtract 51 from 100 to give 49, double it to give 98, subtract that from 100 to give 02, and replace 51 with 02).

Next we need to know 1 - 0.9999999999999999999999902. This is easily seen to be 0.0000000000000000000000098, or 9.8 x 10-24.

And there's our answer.
 

Offline rr100

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Re: What calculator do you use ?
« Reply #294 on: November 22, 2012, 09:08:00 am »
As I mentioned above the question isn't how to do (1-49/10^25)^2 by hand, that is clear. By the way from

(a-b)=a^2-2ab+b^2

you ignored b^2 because b is very small (49/10^25 in our case) and b^2 is even smaller; this is fine (in fact this is THE way you do it on paper usually). However sometimes you just don't want to think how to expand a given expression, sometimes it isn't possible, etc.

I don't want arbitrary/infinite precision, I don't want clever optimizations or a symbolical calculation engine that knows more tricks than most math students, I just want some calculator that uses more than the usual 8-12-16-20 digits for the "significant digits" in the float/scientific numbers. It's not that much a question of resources, the "standard" quad precision will give you roughly 34 digits while using 16 bytes (including for sign and signed exponent). It isn't that much and it wouldn't be even if have it 10x or 20x times larger. But problem is everything (I mean scientific calculators, including TI-89) don't do even half of that.
 

Offline jeroen74

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Re: What calculator do you use ?
« Reply #295 on: November 22, 2012, 01:46:00 pm »
There are programs and languages that can handle as many digits as you like, just limited by the amount of memory there is.
 

Offline amyk

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Re: What calculator do you use ?
« Reply #296 on: November 22, 2012, 05:05:29 pm »
I just want some calculator that uses more than the usual 8-12-16-20 digits for the "significant digits" in the float/scientific numbers. It's not that much a question of resources, the "standard" quad precision will give you roughly 34 digits while using 16 bytes (including for sign and signed exponent). It isn't that much and it wouldn't be even if have it 10x or 20x times larger. But problem is everything (I mean scientific calculators, including TI-89) don't do even half of that.
The good thing about programmable calculators is that you can program most of them to do arbitrary-precision calculations. As for why the stock firmware doesn't: most likely not many people have a use for that, even for scientific calculators. In practice, ~10 significant digits are plenty; even the fundamental constants of the universe are rarely more accurate than that.
 

Online tom66

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Re: What calculator do you use ?
« Reply #297 on: November 22, 2012, 05:40:52 pm »
Calculator with Ubuntu:

(180)×asin(acos(atan(tan(cos(sin(9/180))))))?9
 = 9

It uses bignum, so can be very precise. I think Windows Calculator uses a bignum calculation too.
 

Offline rr100

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Re: What calculator do you use ?
« Reply #298 on: November 22, 2012, 06:03:47 pm »
I know about computer programs, for kicks I just recovered from the very first CD I ever burned Maple V Rel 3 (1994!). It would run in 2MB of RAM (possibly 1) and do miracles. "bc" is the GPL tool of choice for this kind of things, comes with most linuxes by default; this is before we go full blown Sage or something similar.

And yes, I did find something for the programmable calculators: http://www.hpcalc.org/details.php?id=1320
You can look in the PDFs from the archive, LONG.PDF for example, just what the doctor ordered. As opposed to what I've found for TI this one would also do much more than 4 operations, it would do all the usual transcendent ones you need (sin, cos, whatever).

As for practical use I mentioned in the previous example, sometimes you just need to add/substract (or do similar but more complicated stuff, like sin(a)-sin(b)) things of wildly different orders of magnitude. Any scientific calculator knows what 1 is and what 1/10^25 (or even much smaller numbers) is. But if you add them together the result will be on most calculators ... 1. That is fine in itself ... unless you need to substract this "1", in which case you'll get 0 instead of whatever number you're really interested in.
 

Offline rr100

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Re: What calculator do you use ?
« Reply #299 on: November 22, 2012, 08:21:14 pm »
And here's another funny one; I mentioned GNU bc above which is coming with basically any linux for quite a while. Guess what, I can't find the Android port/version!!!
BUT I could find Windows, Windows CE and iPhone versions!!!! WTF?
http://www.appover.com/search/bc-mobile/349255871/
http://gnuwin32.sourceforge.net/packages/bc.htm
http://www.findbestopensource.com/product/yabcalc
 


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