Beefy Boxes and Bandwidth Generously Provided by pair Networks
Pathologically Eclectic Rubbish Lister
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
As quick googling shows, default data type for numpy is 32-bit "single precision" "float"

Are you really sure? I was surprised by your claim that numpy use a default C float. I am a longtime Perl and C hacker and no python expert. But I view the C float type as kind of archaic I use many math libs and the trend is to go past the C double. It would be surprising for a modern lib like numpy to use such a default. Also float() in python means floating point not C float.

Note that I do not really care if tool X is faster that tool Y when the sun, jupiter and the moon are aligned. But I did a bit of web search and could not _quickly_ come up with a definite answer! so I decided to check. Seems that numpy default is a C double:

% steph@kerangi (/tmp/cpanm_t.d) % % python3.8 -c 'import math as m; print(m.sin(float(1)))' 0.8414709848078965 % steph@kerangi (/tmp/cpanm_t.d) % % python3.7 Python 3.7.7 (default, Apr 10 2020, 07:59:19) [GCC 9.3.0] on cygwin Type "help", "copyright", "credits" or "license" for more information. >>> import numpy as np >>> np.float <class 'float'> >>> np.float64 <class 'numpy.float64'> >>> np.float32 <class 'numpy.float32'> >>> print(np.sin(float(1))) 0.8414709848078965 >>> print(np.sin(np.float64(1))) 0.8414709848078965 >>> print(np.sin(np.float32(1))) 0.84147096 >>>

I think that PDL is really a fantastic piece of software and that it is pretty fast. One possible pitfall, common to all C extensions to Perl, is to go back and forth too many times between Perl and C as that can make a computation much slower. It is often possible to avoid it.

hth cheers --sgt

In reply to Re^2: Perl PDL slower than python numpy by sgt
in thread Perl PDL slower than python numpy by fanasy

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



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

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

    How do I use this? | Other CB clients
    Other Users?
    Others perusing the Monastery: (9)
    As of 2021-03-03 18:10 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?
      My favorite kind of desktop background is:











      Results (86 votes). Check out past polls.

      Notices?