Beefy Boxes and Bandwidth Generously Provided by pair Networks
P is for Practical
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

Dana replaced popcnt with mpu_popcount_string in Math::Prime::Util v0.62.

I moved the native popcnt to util.h. mpu_popcount_string is a new function to handle bigints or sufficiently magic input without using a bigint library. It's faster than getting Math::BigInt involved until the numbers get over 500 digits. It should be optimized, but it's not exactly the common case.

It's also useful for making sure we don't get really slow for 64-bit numbers on a 32-bit Perl. Not as fast as forcing 64-bit code, but that's further narrowing down the space -- people on 64-bit machines who install a 32-bit Perl.

Using Math::BigInt to handle a long digit string would be something like:

use Math::BigInt; my $n = "16" x 1000; say 0 + (Math::BigInt->new("$n")->as_bin() =~ tr/1//);
where only the last part is needed if it's already a bigint. Math::GMPz has Rmpz_popcount which is ridiculously fast if the input is already a Math::GMPz object.


In reply to Re^2: How to do popcount (aka Hamming weight) in Perl by danaj
in thread How to do popcount (aka Hamming weight) in Perl by eyepopslikeamosquito

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others lurking in the Monastery: (6)
As of 2022-05-23 01:40 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    Do you prefer to work remotely?



    Results (81 votes). Check out past polls.

    Notices?