https://bugs.documentfoundation.org/show_bug.cgi?id=96821
Bug ID: 96821
Summary: ROUND changes integers when it should not
Product: LibreOffice
Version: 5.0.3.2 release
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: medium
Component: Calc
Assignee: [email protected]
Reporter: [email protected]
ROUND(x,0) should leave integers alone. It does not.
A1=ROUND(B1,0)
B1=C1+1
C1=1024*1024*1024*1024*1024*4
A3=A1-(C1-1000)
B3=B1-(C1-1000)
I see B3=1001 [correct] and A3=1002 [wrong].
Without looking at the code I cannot be 100% certain, but the typical
cause of this trouble is that someone used
x = std::floor (x + 0.5);
thinking that such code rounds to the nearest integer. It does not.
For the value in B1 -- which is 2^52+1 -- as well as the next 2^50
odd numbers, the addition of 0.5 will actually add 1 since that is
the best approximation that fits in a double.
There is one more trouble number: the smallest number that is strictly
less than 0.5. That should round to 0, but the addition yields 1.
The solution likely is to use std::round. However, that function might
not so the desired thing for negative values.
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