There is a website https://www.rskey.org/~mwsebastian/misc ... ensics.htm that describes an algorithm intended to help identify the underlying calculator processor that is being used in a particular calculator brand and model. Often times the chip set from a particular manufacturer was the basis for many different calculator brands. For example, the Texas Mostek RPN chipset was used in the APF Mark 55, Omron 12SR, Privileg SR54CC, Corvus 500 and Sanyo CZ2901. When running the algorithm, all calculators using the same chipset produce the same numeric result. The evaluation algorithm is as follows:
arcsin (arccos (arctan (tan (cos (sin (9)))))) with the calculator set to degrees mode.
The exact result is 9, but the vast number of calculators produce a different result due to peculiarities in the function algorithms and number of digits of accuracy. In the case of the Texas Mostek based calculators, the result is 8.99999614252. So, how do the SwissMicros calculators compare against their HP counterparts ? Well, the DM15 and DM41X are both faithful reproductions of the HP15C and HP41C, so not surprisingly they all produce the same result, which is 9.000417403. However, the DM42 which is based not on the HP42S, but instead on the Free42 emulator, yields 9.00000000000, whereas the HP42S produces 8.99999864267. This suggests, that the math algorithms used in the Free42 emulator and carried over to the DM42 are a bit more precise than the original HP42S. No doubt Thomas Okken can explain this in more detail. Perhaps the SwissMicros claim that the DM42 is the most precise calculator on the worldwide market is not hyperbole.
Calculator Forensics results
Calculator Forensics results
DM15L, S/N 00548. DM42, SN: 00159. DM41X, SN: 00973.
Re: Calculator Forensics results
AFAIK Free42 calculates with 34 digits which is a bit more than what the HP42 uses. This is a simple explanation for different results in that test.
DM42 SN: 00041 β
WP 43S running on this device
HP35, HP45, ..., HP35S, WP 34S, WP 31S, DM16L
WP 43S running on this device
HP35, HP45, ..., HP35S, WP 34S, WP 31S, DM16L

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Re: Calculator Forensics results
Free42 works with about 34 significant digits. If you substrat 9 to the forensic result, you get something like 6e29, which is very small, due to the high precision.
Some others calculators have an extended precision like the sharp pc1475 (20 digits) or the wp34s (32 digits?).
Some others calculators have an extended precision like the sharp pc1475 (20 digits) or the wp34s (32 digits?).
DM15L  DM42  DM41x

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Re: Calculator Forensics results
Note that even though it works with 34 digits, Free42 will only display up to 12 digits, like the HP42S. You can see the contents of the X register at full precision using SHOW, i.e. [Shift] [.]. SHOW will show the full precision for 2 seconds before reverting to the normal display, but you can see it longer by holding down the [.] key.
Re: Calculator Forensics results
So the result with Free42 is 8.999999999999999999999999999937534. Amazing !
DM15L, S/N 00548. DM42, SN: 00159. DM41X, SN: 00973.
Re: Calculator Forensics results
As amazing as WP34S since 2011 and WP43S...
EDIT: Sorry, I forgot a deviation of 1e34 (sic!). The WP34S produces the correctly rounded result ...37535 as well as the WP43S. Merci to Over_score for reminding me.
Last edited by Walter on Tue Dec 01, 2020 9:46 pm, edited 2 times in total.
DM42 SN: 00041 β
WP 43S running on this device
HP35, HP45, ..., HP35S, WP 34S, WP 31S, DM16L
WP 43S running on this device
HP35, HP45, ..., HP35S, WP 34S, WP 31S, DM16L
 Over_score
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 Location: France
Re: Calculator Forensics results
WP43S returns 8.999 999 999 999 999 999 999 999 999 937 535 and this result is correctly rounded
The result of free42 is not!
The correctly rounded intermediate calculations are:
sin(9) = 0.1564344650402308690101053194671669
cos(0.1564344650402308690101053194671669) = 0.9999962727428850241175162050113502
tan(0.9999962727428850241175162050113502) = 0.01745499985548866079139414092834847
arctan(0.01745499985548866079139414092834847) = 0.9999962727428850241175162050113503
arccos(0.9999962727428850241175162050113503) = 0.1564344650402308690101053194660901
arcsin(0.1564344650402308690101053194660901) = 8.999999999999999999999999999937535
The result of free42 is not!
The correctly rounded intermediate calculations are:
sin(9) = 0.1564344650402308690101053194671669
cos(0.1564344650402308690101053194671669) = 0.9999962727428850241175162050113502
tan(0.9999962727428850241175162050113502) = 0.01745499985548866079139414092834847
arctan(0.01745499985548866079139414092834847) = 0.9999962727428850241175162050113503
arccos(0.9999962727428850241175162050113503) = 0.1564344650402308690101053194660901
arcsin(0.1564344650402308690101053194660901) = 8.999999999999999999999999999937535
DM42 SN00284 running free42 & SN03835 running WP43S, DM15L, HP41CV, HP42S, HP35s, WP34S, HP Prime