[Scilab-users] Bitget for int64/uint64

[Jan Åge Langeland]

Thank you, Stéphane

So a workaround is:

b  =uint64(2)^61+1

bb2=uint64(bin2dec(strsplit(strrev(bitstring(b))))');

bb1=bitget(b,1:64);

bb2(1)-bb1(1)

  ans  =  1

A bit of a waste to use uint64 to store single bits, but that is what 
bitget does:

--> typeof(bb1)
  ans  =  "uint64"

Jan

On 2020-02-27 16:55 PM, Stéphane Mottelet wrote:
> But the problem with bitget remains. The new bitstring is ok:
>
> --> bitstring(a)
>  ans  =
>
> "0010000000000000000000000000000000000000000000000000000000000000"
>
> --> bitstring(a+1)
>  ans  =
>
> "0010000000000000000000000000000000000000000000000000000000000001"
>
> S.
>
> Le 27/02/2020 à 16:37, Stéphane Mottelet a écrit :
>> You should generate big ints like this:
>>
>> a=uint64(2)^61
>>
>> S.
>>
>> Le 27/02/2020 à 16:17, JLan a écrit :
>>> I wonder if i have misunderstood the documentation for bitget, or if 
>>> this is
>>> a bug? It seems to me that numbers > 2^53 are still not handled 
>>> correctly.
>>> --> a=uint64(2^61)
>>>   a  =   2305843009213693952
>>> --> b=uint64(2^61)+1
>>>   b  =   2305843009213693953
>>> --> bitget(a,1:64)
>>>   ans  =
>>>           column 1 to 32
>>>    0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0 0  0  
>>> 0  0  0
>>> 0  0  0  0  0  0  0
>>>           column 33 to 64
>>>    0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0 0  0  
>>> 0  0  0
>>> 0  0  0  0  1  0  0
>>>
>>> --> bitget(b,1:64)
>>>   ans  =
>>>           column 1 to 32
>>>    0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0 0  0  
>>> 0  0  0
>>> 0  0  0  0  0  0  0
>>>           column 33 to 64
>>>    0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0 0  0  
>>> 0  0  0
>>> 0  0  0  0  1  0  0
>>>
>>>
>>>
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