Forum Discussion

pratikdarak21's avatar
pratikdarak21
Iron Contributor
Oct 05, 2023

Rounding Issue

Hi,

 

In PowerShell, Round (number, 4) method rounding 0.01275 to 0.0128 as 5 decimal having 5. But, 0.48865 not getting rounded to 0.4887 instead it is giving output as 0.4886. 

 

What causing problem in PowerShell where this anomaly appearing ?

 

Regards,

Pratik

 

.net core
azure
Windows PowerShell

6 Replies

Sort By
  • LainRobertson's avatar
    LainRobertson
    Silver Contributor
    Oct 06, 2023

    pratikdarak21 

     

    You might want to consider casting non-decimal types (double being the most likely default type in PowerShell) to a decimal type (example below) - depending on what the outcome is that you're trying to achieve

     

     

    Strictly-speaking, this isn't a PowerShell "fault/issue", it's below that as a .NET topic. It just happens to impact PowerShell (along with anything else using .NET).

     

    Cheers,

    Lain

  • randriksen_'s avatar
    randriksen_
    Copper Contributor
    Oct 05, 2023

     

    pratikdarak21

     

     

    It seems like it has to do with the second to last decimal. 0.01275 rounds to 0.0128, while 0.48865 rounds to 0.4886. 

    if the second to last decimal is an odd number while the last is a 5, it rounds up. If it is even, it doesn't.

    See here:

     

     

    • pratikdarak21's avatar
      pratikdarak21
      Iron Contributor
      Oct 05, 2023

      randriksen_ 

      Thank you for your reply. But, above explanation getting failed for this value "74.35765". In PowerShell it is rounding to "74.3577".

       

       

      • randriksen_'s avatar
        randriksen_
        Copper Contributor
        Oct 05, 2023

        pratikdarak21 

         

        on this issue it is dependent on both the second and third from last decimals, and there seems to be a static rule for it in the [math]::Round function

        PS C:\bin\git> $n = 74.35715
PS C:\bin\git> 
PS C:\bin\git> for ($i = 0; $i -lt 100; $i++) {
    write-host "For $n the rounding is: "+([math]::Round($n, 4))
    
    $n = $n + 0.0001;
    $n = [math]::Round($n, 5)

}
For 74.35715 the rounding is:  + 74,3572
For 74.35725 the rounding is:  + 74,3572
For 74.35735 the rounding is:  + 74,3574
For 74.35745 the rounding is:  + 74,3574
For 74.35755 the rounding is:  + 74,3576
For 74.35765 the rounding is:  + 74,3577
For 74.35775 the rounding is:  + 74,3578
For 74.35785 the rounding is:  + 74,3578
For 74.35795 the rounding is:  + 74,358
For 74.35805 the rounding is:  + 74,358
For 74.35815 the rounding is:  + 74,3582
For 74.35825 the rounding is:  + 74,3582
For 74.35835 the rounding is:  + 74,3584
For 74.35845 the rounding is:  + 74,3584
For 74.35855 the rounding is:  + 74,3585
For 74.35865 the rounding is:  + 74,3586
For 74.35875 the rounding is:  + 74,3588
For 74.35885 the rounding is:  + 74,3588
For 74.35895 the rounding is:  + 74,3589
For 74.35905 the rounding is:  + 74,359
For 74.35915 the rounding is:  + 74,3592
For 74.35925 the rounding is:  + 74,3592
For 74.35935 the rounding is:  + 74,3594
For 74.35945 the rounding is:  + 74,3594
For 74.35955 the rounding is:  + 74,3596
For 74.35965 the rounding is:  + 74,3596
For 74.35975 the rounding is:  + 74,3598
For 74.35985 the rounding is:  + 74,3598
For 74.35995 the rounding is:  + 74,36
For 74.36005 the rounding is:  + 74,36
For 74.36015 the rounding is:  + 74,3602
For 74.36025 the rounding is:  + 74,3602
For 74.36035 the rounding is:  + 74,3604
For 74.36045 the rounding is:  + 74,3604
For 74.36055 the rounding is:  + 74,3606
For 74.36065 the rounding is:  + 74,3607
For 74.36075 the rounding is:  + 74,3608
For 74.36085 the rounding is:  + 74,3608
For 74.36095 the rounding is:  + 74,361
For 74.36105 the rounding is:  + 74,3611
For 74.36115 the rounding is:  + 74,3612
For 74.36125 the rounding is:  + 74,3612
For 74.36135 the rounding is:  + 74,3614
For 74.36145 the rounding is:  + 74,3614
For 74.36155 the rounding is:  + 74,3615
For 74.36165 the rounding is:  + 74,3616
For 74.36175 the rounding is:  + 74,3618
For 74.36185 the rounding is:  + 74,3618
For 74.36195 the rounding is:  + 74,3619
For 74.36205 the rounding is:  + 74,362
For 74.36215 the rounding is:  + 74,3622
For 74.36225 the rounding is:  + 74,3622
For 74.36235 the rounding is:  + 74,3624
For 74.36245 the rounding is:  + 74,3624
For 74.36255 the rounding is:  + 74,3626
For 74.36265 the rounding is:  + 74,3626
For 74.36275 the rounding is:  + 74,3628
For 74.36285 the rounding is:  + 74,3628
For 74.36295 the rounding is:  + 74,363
For 74.36305 the rounding is:  + 74,363
For 74.36315 the rounding is:  + 74,3632
For 74.36325 the rounding is:  + 74,3632
For 74.36335 the rounding is:  + 74,3634
For 74.36345 the rounding is:  + 74,3634
For 74.36355 the rounding is:  + 74,3636
For 74.36365 the rounding is:  + 74,3637
For 74.36375 the rounding is:  + 74,3638
For 74.36385 the rounding is:  + 74,3638
For 74.36395 the rounding is:  + 74,364
For 74.36405 the rounding is:  + 74,3641
For 74.36415 the rounding is:  + 74,3642
For 74.36425 the rounding is:  + 74,3642
For 74.36435 the rounding is:  + 74,3644
For 74.36445 the rounding is:  + 74,3644
For 74.36455 the rounding is:  + 74,3645
For 74.36465 the rounding is:  + 74,3646
For 74.36475 the rounding is:  + 74,3648
For 74.36485 the rounding is:  + 74,3648
For 74.36495 the rounding is:  + 74,3649
For 74.36505 the rounding is:  + 74,365
For 74.36515 the rounding is:  + 74,3652
For 74.36525 the rounding is:  + 74,3652
For 74.36535 the rounding is:  + 74,3654
For 74.36545 the rounding is:  + 74,3654
For 74.36555 the rounding is:  + 74,3656
For 74.36565 the rounding is:  + 74,3656
For 74.36575 the rounding is:  + 74,3658
For 74.36585 the rounding is:  + 74,3658
For 74.36595 the rounding is:  + 74,366
For 74.36605 the rounding is:  + 74,366
For 74.36615 the rounding is:  + 74,3662
For 74.36625 the rounding is:  + 74,3662
For 74.36635 the rounding is:  + 74,3664
For 74.36645 the rounding is:  + 74,3664
For 74.36655 the rounding is:  + 74,3666
For 74.36665 the rounding is:  + 74,3667
For 74.36675 the rounding is:  + 74,3668
For 74.36685 the rounding is:  + 74,3668
For 74.36695 the rounding is:  + 74,367
For 74.36705 the rounding is:  + 74,3671

Resources