Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl: the Markov chain saw
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??
I wanted something closer to "Engineering notation".... I'd like to be able to make the width a parameter (instead of fixed at 9). Being able to go as low as 7 (or even 6) would be way cool.

this code should meet those requirements. at least, the mantissa width is fixed, the exponent width varies. it should be easy enough to modify this code to suit your needs, if you wish.

i used your test suite, too.

#!/usr/bin/perl use strict; use warnings; $|++; Main(); exit; ## adapted from code found at: http://www.cs.tut.fi/~jkorpela/c/eng.ht +ml sub eng { my( $num, $digits )= @_; ## default to smallest number of digits allowing fixed width manti +ssa (4) $digits= defined $digits && 3 < $digits ? $digits : 4; my $neg; if( 0 > $num ) { $neg= 'true'; $num= -$num; } 0 == $num and return sprintf '+%.*fe+%s' => $digits - 1, $num, 0; my $exp= 0 != $num ## perl's log() is natural log, convert to common log ? int( log($num) / log(10) ) ## short-circuit: can't do log(0) : 0; ## tricky integer casting ahead... $exp= 0 < $exp ? int( ( int( $exp / 3 ) ) * 3 ) : int( int( ( -$exp + 3 ) / 3 ) * -3 ); $num *= 10 ** -$exp; if( 1000 <= $num ) { $num /= 1000; $exp += 3; } elsif( 100 <= $num ) { $digits -= 2; } elsif( 10 <= $num ) { $digits -= 1; } 0 <= $exp and $exp= '+' . $exp; return ( $neg ? '-' : '+' ) . sprintf '%.*fe%s' => $digits - 1, $num, $exp; } sub Main { my $digits= 2; for my $exp ( -101..-98, -11, -10..11, 98..101 ) { for my $sign ( '', '-' ) { my $num= 0 + ( $sign . "5.555555555e" . $exp ); printf "%-20s (%s)\n", $num, eng( $num, $digits ); } } for my $exp ( -10..11 ) { for my $sign ( '', '-' ) { my $num= 0 + ( $sign . "1e" . $exp ); printf "%-20s (%s)\n", $num, eng( $num, $digits ); printf "%-20s (%s)\n", 0, eng( 0, $digits ) if 1 == $num; } } }

~Particle *accelerates*


In reply to Re: Display floating point numbers in compact, fixed-width format by particle
in thread Display floating point numbers in compact, fixed-width format by tye

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 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?Last hourOther CB clients
Other Users?
Others perusing the Monastery: (5)
As of 2024-03-29 14:24 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found