Re: Preparing the release of Gambas 3.20

[Benoît Minisini <benoit.minisini@xxxxxxxxxxxxxxxx>]

Le 04/01/2025 à 09:48, Christof Thalhofer a écrit :
> Am 04.01.25 um 01:44 schrieb Benoît Minisini:
>
> > And for sure someone will find last minute blocking bugs...
>
> You could find one by yourself if you would have ran './test-fast'.
>
> > # 2 tests failed:
> > # 2: OldBugs.BugStringToFloatConversion.25 -- # 4: 
> > OldBugs.BugStringToFloatConversion.29 -- #
> > # FAILED
>
> Alles Gute
>
> Christof Thalhofer

This test is problematic.

You cannot be sure that `Round(19.9,-2) = 19.9`, because 19.9 has no 
exact binary representation, neither 10^-2.

As the algorithm of Round() slightly changed, the test does not pass 
anymore.

The "=" operator should almost never applied to floating point numbers.

It's a difficult problem to compare floating point numbers. Two 
different floating point numbers may have the same string representation.

For example, you can see in the 'gb.gui.base' 'PaintSmooth' module that 
implements the algorithm for the new 'Paint.SmoothPolyline()' method, 
that floating points are compared using that function:

Private Sub SameFloat(X As Float, Y As Float) As Boolean

  Dim F As Float

  F = Max(Abs(X), Abs(Y))
  If F = 0 Then
    Return True
  Else
    Return Abs(X - Y) / F < 1E-6
  Endif

End

Regards,

--
Benoît Minisini.