Verification of Customfileds


I have some troubles with the verification of custom fields. I do the verification by using Excel. We use the Empower data precision of 14 decimal places for the external calculation. We have the problem, that we have differences between Excel and Empower. The results differs from each other at the 6 or 7 decimal place.

For testing I have build a custom field detecor drift/ Scale to µV.

Detector drift is: 0.00054949483469

The result calculated via Excel is:  549.49483469000000

The result Empower calulates is: 549.494836073896

Why do I have These differences? Does Empower calculation with more than 14 decimal places in backround?



Best Answer

  • Accepted Answer
    When verifying custom fields you have to take into account two things. Firstly, each individual section of a cf formula is always going to use the full decimal places within Empower to calculate the result. For example, Area/Height for a peak cf will divide the full area of the peak by the full height of the peak.

    Secondly, and crucially, Empower actually calculates values to 17 significant digits but only displays a maximum of 14 digits so a peak amount may display as 12.43156776518765 whereas the entire number calculated by Oracle, which is the engine behind Empower, is actually 12.43156776518764903. The last 3 digits arent displayed. Since very few output calculations demand anything close to absolute identical values up to 14 places of decimals, the best way to verify custom field calculations is to copy in 14 decimals for all fields of your formula for example Detector Noise*12 using an online calculator set to a precision of 14 and your results will be almost identical. Any tiny differences are due to the actual 17 digits being considered by Empower in the background.

    As i said, the only way you are going to notice this is if you track every single number to 14 decimals then compare and contrast with Excel or a calculator! If your custom field formula does demand a high degree of precision then make sure you set the precision of the cf to a suitably high value. Remember, precision just displays the value to the desired number of places. The full amounts are always used in the background.


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