in reply to Re: subtraction issue
in thread subtraction issue

Anonymous: Previous to Perl version 5.22.0, you can use a format like '%0.20f'.

Give a man a fish:  <%-{-{-{-<

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Re^3: subtraction issue
by syphilis (Archbishop) on Jan 27, 2017 at 09:00 UTC
    Previous to Perl version 5.22.0, you can use a format like '%0.20f'

    Yes, I think that's a good enough replacement for most purposes - and a useful addition to my post.

    However, it's not guaranteed to give you the exact base 10 value stored in the double - whereas %a will give you the exact (base 16) value.

    Cheers,
    Rob
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      Feel free to ignore this post. I just couldn't help myself (I needed the coffee-break distraction, apparently)

      Read more... (11 kB)
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        it takes n fixed-point decimal digits to exactly represent an n-bit fixed-point fractional binary number

        Thank you for correcting me ... but shouldn't that be "n+1 fixed-point decimal digits" ? 
        use strict;
use warnings;
use Math::MPFR qw(:mpfr);

Rmpfr_set_default_prec(1000);

my $d = 1 / 11;
my $x = Math::MPFR->new($d);

print "$x\n", length($x), "\n";

# (print() removes trailing zeros.)
# Outputs:
9.09090909090909116141432377844466827809810638427734375e-2
58

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        Take out the "." and the "e-2" and we're left with 54 decimal digits.

        Cheers,
        Rob
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