Re: flags in a bitmap

[switched from user to dev]

On 2025-07-04 15:51, Bill Allombert wrote:
> On Fri, Jul 04, 2025 at 12:38:59PM +0200, Ruud H.G. van Tol wrote:
>>> ? install(bitset,vWL)
>>> ? x=2^(2^20);
>>> ? forprime(p=2,2^20,bitset(~x,p))
>>>     ***   last result computed in 8 ms.
>>> ? my(S=0);for(i=0,2^20-1,S+=bittest(x,i));S
>>> %16 = 82025
>>>     ***   last result computed in 159 ms.
>> That indeed looks good, and I can test it.
> Great, I have made a GIT branch bill-bitset
>
> commit 8632eaf7528554234aaa90d9a503476452cbd736 (HEAD -> bill-bitset, origin/bill-bitset, master)
> Author: Bill Allombert <[email protected]>
> Date:   Thu Jul 3 23:57:00 2025 +0200
>
>      New GP functions bitset, bitclear

Thanks. First (minor) remark:


-Help: bitclear(~n,i): clear bit i of n (in place)
+Help: bitclear(~x,n): clear bit n of x (in place)

-Help: bitset(~n,i): set bit i of n in place
+Help: bitset(~x,n): set bit n of x in place


to align it with bittest, and with the code.

-- Ruud