Wrong documentation for the round() function

[dan-covaliu]

The doc states that the round is using banker's rounding. However logging the following statements: toString(round(23.5)) + ' ' + toString(round(-23.5)) + ' ' + toString(round(24.5)) + ' ' + toString(round(-24.5)) + ' ' + toString(round(22.5)) + ' ' + toString(round(-22.5)) + ' ' + toString(round(21.5)) + ' ' + toString(round(-21.5)) obtains: 24,-24,25,-25,23,-23,22,-22, which looks more like "half away from zero" rounding, also called commercial rounding (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).

[Rvthof]

Hi Dan,

There is an option in your Settings where you can switch between these two. Can you check if that's set correctly?

It is maybe a good idea to add this to the docs for the round function, to make this more clear.

[Adam-Dupaski]

Documentation updated: https://docs.mendix.com/refguide/mathematical-function-calls#output-2

Closing issue.

[dan-covaliu]

Hi Adam,

I knew about the setting… Thank you for making the documentation more precise. Still, I detect an error in the banker’s rounding definition. These are tests conducted using each setting, in turn:

Half away from zero: toString(round(200000 div 72,2)): 2777.78 toString(round(2777.775, 2)): 2777.78 toString(round(88.725, 2)): 88.73 toString(round(23.5)): 24 toString(round(-23.5)): -24 toString(round(24.5)): 25 toString(round(-24.5)): -25 toString(round(22.5)): 23 toString(round(-22.5)): -23 toString(round(21.5)): 22 toString(round(-21.5)): -22

Half to the nearest EVEN number: toString(round(200000 div 72,2)): 2777.78 toString(round(2777.775, 2)): 2777.78 toString(round(88.725, 2)): 88.72 toString(round(23.5)): 24 toString(round(-23.5)): -24 toString(round(24.5)): 24 toString(round(-24.5)): -24 toString(round(22.5)): 22 toString(round(-22.5)): -22 toString(round(21.5)): 22 toString(round(-21.5)): -22

As you can see EVEN numbers are 22,-22, 24 and -24, not 23 and -23

Regards, | Cordialement,

Dan Covaliu Software Integrator and Designer | Intégrateur et concepteur de logiciel T 514-496-1479 F 514-496-9344

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From: Adam Dupaski [mailto:notifications@github.com] Sent: June 19, 2017 4:32 AM To: mendix/docs docs@noreply.github.com Cc: COVALIU, Dan (MTL) Dan.Covaliu@bdc.ca; Author author@noreply.github.com Subject: Re: [mendix/docs] Wrong documentation for the round() function (#373)

Documentation updated: https://docs.mendix.com/refguide/mathematical-function-calls#output-2

Closing issue.

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[Adam-Dupaski]

Hi Dan, Thanks for the message. I've clarified the example in the documentation: https://docs.mendix.com/refguide/mathematical-function-calls#output-2 Cheers.

[Adam-Dupaski]

Hi Dan, one more thing: please note that you can contribute to the Mendix documentation yourself by sending a pull request with any changes/suggestions. See here for more details!