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A comment on Windows Calculator invalid input with 10^x function.

Re:Windows Calculator invalid input with 10^x function by gabriel34 on Thursday August 02, 2018 @04:55PM (#17675391)
Seems the issue occurs at some range (10^0,39794 - ?]

  10^0,43407 - Invalid Input
  10^0,00001 - OK
  10^0,50001 - Invalid Input
  10^0,40001 - Invalid Input
  10^0,30001 - OK
  10^0,35001 - OK
  10^0,39999 - Invalid Input
  10^0,37501 - OK
  10^0,38751 - OK
  10^0,39375 - OK
  10^0,39794 - OK
  10^0,39795 - Invalid Input
But when I tried better approximations things got weird

  10^0,397941 - Invalid Input
  10^0,397940000001 - Invalid Input
Seems six or more decimal places result in Invalid Input

  10^0,39375 - OK
  10^0,393751 - Invalid Input
  10^0,39376 - OK
Even well outside the range

  10^0,123456 - Invalid Input
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Re:Windows Calculator invalid input with 10^x function by psyklic on Thursday August 02, 2018 @05:12PM (#17675519)
There seems to be a clear pattern for > 5 digits after the decimal:

  5 digits - Valid: <=0.39794, Invalid: >=0.39795
    10^0.39794 < 2.5
    10^0.39795 > 2.5

  6 digits - Valid: <=0.043429, Invalid: >=0.043431
  7 digits - Valid: <=0.0043429, Invalid: >=0.0043431
  8 digits - Valid: <=0.00043429, Invalid: >=0.00043431
The pattern seems to continue as the number of decimal places increases.
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Re:Windows Calculator invalid input with 10^x function by barbegal on Thursday August 02, 2018 @05:53PM (#17675777)
10^0.043429 ~= e^0.1

10^0.0043429 ~= e^0.01

10^0.00043429 ~= e^0.001

So that gives some insight into the algorithm that is being used

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Re:Windows Calculator invalid input with 10^x function by gabriel34 on Thursday August 02, 2018 @07:18PM (#17676246)
Using this we can actually predict the smallest exponent that fails for other bases:

  base	exponent (6 digits)
  10	0.043429
  11	0.041703
  12	0.040243
  2	0.144271
  3	0.091024
  4	0.072135
  1000	0.014476
(the calculated exponent for two is actually 0.144270, but since it ends in zero the first failure occurs at 0.144271)
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Re:Windows Calculator invalid input with 10^x function by imran3740 on Thursday August 02, 2018 @10:07PM (#17676848)
Just checked, calc fails at 11^0.41703 (curiously not at 41703, but 41704, maybe a floating point thing). Maybe it changes base to e and uses the Taylor series for e^x, but fails if x is too precise for what it expects?
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Re:Windows Calculator invalid input with 10^x function by psyklic on Thursday August 02, 2018 @11:44PM (#17677157)
Fantastic, that confirms it! And kudos to barbegal for recognizing the base.
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Re:Windows Calculator invalid input with 10^x function by craftyguy on Thursday August 02, 2018 @06:39PM (#17676063)
if only the source code were publicly available, then the real problem could be realized, patches proposed, etc. enjoy waiting on microsoft to patch it, they're probably too busy 'loving open source.'
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Re:Windows Calculator invalid input with 10^x function by userbinator on Thursday August 02, 2018 @08:09PM (#17676457)
Even from a strictly business standpoint it certainly makes sense to open-source things like the calculator, since I doubt the source contains any proprietary IP that gives it any particular competitive advantage --- and in the "basic calculator app" space, there is certainly a lot of competition.

Then again, the fact that they managed to break one of the most conceptually simple applications that comes with Windows --- for seemingly no good reason at all --- speaks volumes about the quality of MS products these days...

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Re:Windows Calculator invalid input with 10^x function by zeusk on Thursday August 02, 2018 @11:06PM (#17677033)
https://www.macrumors.com/2017/10/30/ios-11-2-beta-fixes-cal...

http://nuclearrambo.com/wordpress/google-calculator-bug-3999...

Things break.

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Re:Windows Calculator invalid input with 10^x function by userbinator on Thursday August 02, 2018 @11:34PM (#17677125)
I'm not sure what you're trying to say. Are we supposed to consider it normal that something which used to work is now broken? I hope not, especially with something as well-defined as a calculator.
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Re:Windows Calculator invalid input with 10^x function by zeusk on Friday August 03, 2018 @12:34AM (#17677299)
> Then again, the fact that they managed to break one of the most conceptually simple applications that comes with Windows --- for seemingly no good reason at all --- speaks volumes about the quality of MS products these days...
[ Parent | on HN ]