Hi, I spent some time figuring out how the Roune with x decimals function works. I finally was able to understand it and it will save me a lot of trouble in the future. Here are my thoughts, please someone correct if I am wrong. I am talking about this function: [image] I thought this was mere…

Nice catch! Can you make this a feature request in the github?

[image] jbonet007: The problem for me was when Getting this information from Firebase and trying to “Round to 2 decimals” again… then it crashed. Can you tell us a little more about what was happening here please @jbonet007 ? When you get data from a Firebase object, that data will be a strin…

Hi @domhnallohanlon , I was not aware all data from firebase should be treated as a string, thanks for the hint. Here is one potential issue independent from Firebase In case below Button 1 crashes and Button 2 works fine. [image] Of course in this case rounding twice is not necessary, but the…

[image] jbonet007: like the function, is just the interpretation that is misleading. [image] Maybe changing the wording to truncates? It doesn’t round it truncates, right

actually it rounds, but with inconsistent rules! (it’s probably a consistent rule but it’s applying to the fractional bit representation of the number, instead of decimal), 3.1449 with 2 decimal places => 3.14 3.1451 with 2 decimal places => 3.15 3.145 with 2 decimal places => 3.15 3.155 with 2 …

Thank you for your research. Indeed, there is a problem with the rounding rules! You’re right. The loss of accuracy is due to the fact that fractional numbers are stored in binary form, and not in decimal form, as users often understand. For this reason, 0.1 + 0.2 is not equal to 0.3 (if someone di…

I also noticed the following behavior, is it also related to the same issue? this is the reason I needed to round twice in previous example: [image] Click 1: 10.04 Click 2: 10.44 Click 3: 14.440000000000000001

Yes, this is also due to a loss of accuracy. For this reason, you need to work carefully with expressions that use fractional numbers. To avoid errors it is necessary to use rounding.

I want to draw attention to the fact that the loss of accuracy occurs only if a fractional number cannot be stored accurately in the binary system. If a fractional number allows to store it precisely, there will be no error, for example, 0.2 + 0.2 is equal to 0.4.

Round with x decimals behaviour

Questions about Thunkable X

jared May 21, 2020, 10:11pm 7

Thanks!!

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Round with x decimals behaviour

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