Hi Jon, Thanks, again. However, I took a different route. I looked at the response to Shlomi's question on this in perl5-porters. The responder suggested adding
use POSIX qw(strtod); and then replacing your calls to "parse_sci_note" with "strtod". My code works now. Any drawback to this method? On Tue, Sep 21, 2010 at 11:00 AM, Jon Hermansen <jon.herman...@gmail.com>wrote: > Hi Abu, > > I got the idea for my variation on your script from a forum, where > someone is parsing a list of numbers in scientific notation just as > you are. > > > http://www.gamedev.net/community/forums/topic.asp?topic_id=537620&whichpage=1� > > Until the bug is fixed, here's a workaround: > > --- > > #!/usr/bin/perl > > use strict; > use warnings; > > my $d1 = parse_sci_note('6.892964e-309'); > my $d2 = parse_sci_note('1.102874e-307'); > > my $sum = $d1 + $d2; > > printf("d1 = %e\n", $d1); > printf("d2 = %e\n", $d2); > printf("sum = %e\n", $sum); > > sub parse_sci_note { > # argumnet must be a string to work around perl bug > my $arg = shift; > $arg =~ s/[eE]/\*10\*\*/; > return eval($arg); > } > > --- > > The perl documentation clearly shows scientific notation used here: > > http://perldoc.perl.org/perldata.html#Scalar-value-constructors > > so I'd say it definitely is a bug. > > On Tue, Sep 21, 2010 at 10:25 AM, Abu Yoav <abuy...@gmail.com> wrote: > > Hi Jon and Shlomi, > > > > Thanks! > > > > Jon: > > Actually, in my case, it's a bit more complicated than that. I read the > > numbers from a file, and there they are in the standard C notation that > I've > > used in my example. > > > > Shlomi: > > Thanks for the heads up about how to write good code. I'm still very much > a > > beginner... > > Also, thanks for consulting perl5-porters. If it is a bug, and it is > fixed, > > then I will indeed port my C code to perl. > > > > > > > > On Mon, Sep 20, 2010 at 11:40 PM, Jon Hermansen <jon.herman...@gmail.com > > > > wrote: > >> > >> Hi Abu, > >> This code works for me: > >> > >> #!/usr/bin/perl > >> > >> my $d1, $d2, $sum; > >> > >> $d1 = 6.892964 * 10 ** -309; > >> $d2 = 1.102874 * 10 ** -307; > >> > >> $sum = $d1 + $d2; > >> > >> printf("d1 = %e\n", $d1); > >> printf("d2 = %e\n", $d2); > >> printf("sum = %e\n", $sum); > >> > >> On Mon, Sep 20, 2010 at 1:30 PM, Abu Yoav <abuy...@gmail.com> wrote: > >> > Hi, > >> > > >> > I wanted to port a small c program to perl. However, the two programs > >> > behave > >> > differently with respect to very small "double" values. The behavior > >> > seems > >> > like a bug to me, but since I'm very new to perl, I thought I might > ask > >> > the > >> > list first. > >> > > >> > Relevant code and output follows. Thanks! > >> > > >> > --- c code --- > >> > #include<stdio.h> > >> > > >> > int main (int argc, char** argv) > >> > { > >> > double d1, d2, sum; > >> > > >> > d1 = 6.892964e-309; > >> > d2 = 1.102874e-307; > >> > > >> > sum = d1 + d2; > >> > > >> > printf("d1 = %e\n", d1); > >> > printf("d2 = %e\n", d2); > >> > printf("sum = %e\n", sum); > >> > > >> > return 0; > >> > } > >> > > >> > --- perl code --- > >> > #!/usr/bin/perl > >> > > >> > my $d1, $d2, $sum; > >> > > >> > $d1 = "6.892964e-309"; > >> > $d2 = "1.102874e-307"; > >> > > >> > $sum = $d1 + $d2; > >> > > >> > printf("d1 = %e\n", $d1); > >> > printf("d2 = %e\n", $d2); > >> > printf("sum = %e\n", $sum); > >> > > >> > --- c output --- > >> > d1 = 6.892964e-309 > >> > d2 = 1.102874e-307 > >> > sum = 1.171804e-307 > >> > > >> > --- perl output --- > >> > d1 = 0.000000e+00 > >> > d2 = 1.000000e-307 > >> > sum = 1.000000e-307 > >> > > > > > >
