topic Re: Round() function giving sometimes incorrect results in QlikView

Round() function giving sometimes incorrect results

Wed, 02 Jul 2014 11:27:56 GMT

Hello

Please look into attached .qvw file.

There is a text object within, rounding numbers to two decimal places, some of them correctly, some of them incorrectly.

Can anybody explain it?

Is it known bug?

QV 11.20.12018.0 SR3 64-bit

Many thanks in advance.

Vlastimil

Re: Round() function giving sometimes incorrect results

maxgro — Wed, 02 Jul 2014 11:30:12 GMT

http://community.qlik.com/blogs/qlikviewdesignblog/2013/12/17/rounding-errors

Re: Round() function giving sometimes incorrect results

hic — Wed, 02 Jul 2014 11:51:06 GMT

The short answer is: No it is not an error. This is expected behaviour of software that uses a binary number representation internally. What happens is that Round() rounds to nearest binary number - not to nearest decimal number.

Read the blog post behind Massimo's link, and you will understand.

HIC

Re: Round() function giving sometimes incorrect results

Wed, 02 Jul 2014 11:54:40 GMT

Thanks to all.

Vlasta

Re: Round() function giving sometimes incorrect results

Anonymous — Wed, 02 Jul 2014 12:02:29 GMT

This expression works, as in adding 0.001 to number and rounding to 0.01.

round( (1.235+0.0001 ), 0.01 )

It is horrible frig, maybe somebody will have a more elegant solution.

Best Regards, Bill

Re: Round() function giving sometimes incorrect results

stevedark — Fri, 04 Jul 2014 08:47:02 GMT

Taking Bill Markham 's idea further. You could add a much smaller number, to ensure you don't get a different number to what you expect.

You can also put this into a variable. So, if you create a variable called vMyRound with the following in:

round($1 + 0.0000000001, $2)

You can then call it in an expression like this:

$(vMyRound(14.235, 0.01))

The technique of passing parameters into a variable is incredibly useful, thanks to Stephen Redmond for bringing it to my attention some time back.

Steve