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Alteryx designer Discussions

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SOLVED

Decimal precision - Alteryx finds additional precision where hidden/does not exist?

Alteryx Partner

I have an .xlsx file with values where there are two digits after the decimal. I have checked in excel, and I cannot see anything beyond that.  

 

For example, the value: 917285.43 in becomes 917285.43000000000000000000000000000000000000000000000000 when I take it x number of places past the decimal point in Excel.

 

However, when I bring into Alteryx and take it to 40 digits past the decimal point, Alteryx gives:

 

917285.4300000000512227416038513183593750000000


Does anyone know why?  I think the Excel was outputted from a database.  Is it that Alteryx can read these additional digits but excel cannot? 

 

 

 

 

Quasar
Quasar

Hello @bb213 - Good catch, I think this issue lies, irrespective if the data is from Database, Excel or Text Input.

 

I tried to do a text input with a value of 50.85 and increase the decimal places and this is what I got.

 

50.8500000000000014210854715202003717422485

 

Looks like a Bug! You can log it here - Here

 

decimal.PNG

Alteryx Partner

Very interesting.  What version of Alteryx are you using?  Can you tell me if you get the same result in this workflow? 

 

It appears Alteryx doesn't know how to divide. 

Quasar
Quasar

Same Issue.... Alteryx 2018.2

Highlighted
Alteryx Partner

I don't see where I can submit a bug using that link. 

Alteryx
Alteryx

What data type are you using? This sounds like normal Floating Point Imprecision.

Regards,
Stephen Ruhl
Customer Support Engineer

Alteryx Partner

It's not that it's imprecise- it's that it's wrong.  You can use any numeric type.  Also, you can check my workflow. 

Alteryx
Alteryx

Looks like our last posts were lost to the ether.

 

It looks like Excel just takes your last explicit digit and pads it with zeros to hide the floating point issue. Unless you are using the FixedDecimal data type you will see this issue. It is a known characteristic of computer processing and number storage. Alteryx mentions it in their Help FAQ: I am using a simple filter:[Value] > 2. Yet I am getting values equal to 2 in my TRUE stream. Is this a bug?

 

There's more information on floating point math in Wikipedia.

Regards,
Stephen Ruhl
Customer Support Engineer

Alteryx Partner

Please go to an online scientific calculator, perform the operation there, and tell me what answer you get. 

Quasar
Quasar

Hello @StephenR - Thanks for the information... Something new to learn.

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