# New Ticket Created by Dan Kogai # Please include the string: [perl #127126] # in the subject line of all future correspondence about this issue. # <URL: https://rt.perl.org/Ticket/Display.html?id=127126 >
Oops, the previous message does not contain the patch so I am submitting again. Use the patch below or just pull https://github.com/rakudo/rakudo/pull/667 . ==== I am glad perl6 supports complex numbers natively. What I am not glad is that its definition of i does not agree with mathematics: % perl6 > sqrt(-1+0i) 6.12323399573677e-17+1i Though (-1+0i)**0.5 != 1i for most other platforms, they still get sqrt(-1+0i) right: % python Python 2.7.10 (default, Oct 23 2015, 18:05:06) [GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> from cmath import * >>> sqrt(-1+0j) 1j >>> (-1+0j)**0.5 (6.123233995736766e-17+1j) >>> ^D % irb irb(main):001:0> require 'cmath' => true irb(main):002:0> CMath.sqrt(-1) => (0+1.0i) irb(main):003:0> ^D % perl -MMath::Complex -dE 1 Loading DB routines from perl5db.pl version 1.49 Editor support available. Enter h or 'h h' for help, or 'man perldebug' for more help. main::(-e:1): 1 DB<1> p sqrt(-1+0*i) i DB<2> p (-1+0*i)**0.5 6.12323399573677e-17+i So here is the patch that defines sqrt in sqrt. Dan the Complex Perl6 Newbie --- src/core/Complex.pm | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/src/core/Complex.pm b/src/core/Complex.pm index 8314025..74b1d5b 100644 --- a/src/core/Complex.pm +++ b/src/core/Complex.pm @@ -80,8 +80,10 @@ my class Complex is Cool does Numeric { } method sqrt(Complex:D:) { - my Num ($mag, $angle) = self.polar; - $mag.sqrt.unpolar($angle/2); + my Num $abs = self.abs; + my Num $re = (($abs + self.re)/2).sqrt; + my Num $im = (($abs - self.re)/2).sqrt; + Complex.new($re, self.im < 0 ?? -$im !! $im); } multi method exp(Complex:D:) { -- 2.5.4 (Apple Git-61)
