2 ^ 62 = 4611686018427387905 ???

[timsky]

$iInt64 = Int(2 ^ 62, 2)
ConsoleWrite($iInt64 & @lf)

= 4611686018427387905

Bug starts at 2 ^ 49 and further.

2 ^ 63 gives -9223372036854775808 as result. Why negative?

AutoIt 3.3.14.5.

PS:

I also found other math bug(s) in more complex code but can not determine where. Maybe it is related.

Edited March 11, 2019 by timsky

[Nine]

16 minutes ago, timsky said:

2 ^ 63 gives -9223372036854775808 as result. Why negative?

Leftmost bit = 1 thus negative ?  But you got definitively a bug here. You should report it in bug tracker.

Try :

MsgBox ($MB_SYSTEMMODAL,"",Hex (2^48))
MsgBox ($MB_SYSTEMMODAL,"",Hex (2^49))

Obvious. 

[BrewManNH]

From the help file for Int()

Quote

This function makes minor corrections to floating point numbers to account for the imprecise nature of floating point numbers. For example, the floating point expression 0.7 + 0.2 + 0.1 produces a floating point number that is not quite 1.0. Int() corrects for this anomaly, however, certain extremely rare circumstances may lead to Int() returning an unexpected value (the odds of getting an unexpected value are less than if Int() did not attempt any correction at all).

 

[Bilgus]

How about an iPow function?

 

ConsoleWrite(iPow(2, 49) & @CRLF)
ConsoleWrite(iPow(2, 50) & @CRLF)
ConsoleWrite(iPow(2, 62) & @CRLF)
ConsoleWrite(iPow(2, 63) & @CRLF)

Func iPow($iBase, $iExp, $sType = "UINT64")
    $tRes = DllStructCreate($sType)
    DllStructSetData($tRes, 1, 1)

    While $iExp > 0
        If BitAND($iExp, 1) = 1 Then
            DllStructSetData($tRes, 1, DllStructGetData($tRes, 1) * $iBase)
        EndIf
        $iExp = BitShift($iExp, 1) ;Right shift 1
        $iBase *= $iBase
    WEnd
    Return DllStructGetData($tRes, 1)
EndFunc   ;==>iPow

562949953421312
1125899906842624
4611686018427387904
-9223372036854775808

note the 2 ^ 63 still outputs a negative number but that is a limitation of Autoit not the algorithm and further processing would be needed

[Bilgus]

Even better..

 

[BrewManNH]

17 minutes ago, Bilgus said:

but that is a limitation of Autoit

That is a limitation of working with floating point numbers in any system.

[Bilgus]

Well yes but I'm saying since the underlying datatype in autoit is signed even though the number is UINT64 it is displayed as INT64

[timsky]

Bilgus, thanks for iPow and operator64 

Ticket is there: https://www.autoitscript.com/trac/autoit/ticket/3703