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August 10, 2019 01:31Subject:

Re: Help with Perl 6 scriptMessage ID:

CAA99HCz7pky3DM_UfXug9WTj5mxRqYAReg0oWQG_Y_xZ03Tonw@mail.gmail.comHi Rui, Have you considered just installing Perl 6 ? https://rakudo.org https://www.perl6.org Spoiler alert: the Perl6 code you posted works with no errors on my Perl6 install. Best Regards, Bill. On Thu, Aug 8, 2019 at 1:07 PM Rui Fernandes <rui.kepler@gmail.com> wrote: > > Greetings > > I have this Perl 6 script from Rosetta, which I wanted to run on Perl 5 (due to the Active Sate Perl and App version that I have). However, several syntax errors appear given the difference (some) in language.Here's the script: > > --- > > # Simple Vector implementation > multi infix:<+>(@a, @b) { @a Z+ @b } > multi infix:<->(@a, @b) { @a Z- @b } > multi infix:<*>($r, @a) { $r X* @a } > multi infix:</>(@a, $r) { @a X/ $r } > sub norm { sqrt [+] @_ X** 2 } > > # Runge-Kutta stuff > sub runge-kutta(&yp) { > return -> \t, \y, \δt { > my $a = δt * yp( t, y ); > my $b = δt * yp( t + δt/2, y + $a/2 ); > my $c = δt * yp( t + δt/2, y + $b/2 ); > my $d = δt * yp( t + δt, y + $c ); > ($a + 2*($b + $c) + $d) / 6; > } > } > > # gravitational constant > constant G = 6.674e-11; > # astronomical unit > constant au = 150e9; > > # time constants in seconds > constant year = 365.25*24*60*60; > constant month = 21*24*60*60; > > # masses in kg > constant $ma = 2e30; # Sun > constant $mb = 6e24; # Earth > constant $mc = 7.34e22; # Moon > > my &dABC = runge-kutta my &f = sub ( $t, @ABC ) { > my @a = @ABC[0..2]; > my @b = @ABC[3..5]; > my @c = @ABC[6..8]; > > my $ab = norm(@a - @b); > my $ac = norm(@a - @c); > my $bc = norm(@b - @c); > > return [ > flat > @ABC[@(9..17)], > map G * *, > $mb/$ab**3 * (@b - @a) + $mc/$ac**3 * (@c - @a), > $ma/$ab**3 * (@a - @b) + $mc/$bc**3 * (@c - @b), > $ma/$ac**3 * (@a - @c) + $mb/$bc**3 * (@b - @c); > ]; > } > > loop ( > my ($t, @ABC) = 0, > 0, 0, 0, # Sun position > au, 0, 0, # Earth position > 0.998*au, 0, 0, # Moon position > 0, 0, 0, # Sun speed > 0, 2*pi*au/year, 0, # Earth speed > 0, 2*pi*(au/year + 0.002*au/month), 0 # Moon speed > ; > $t < .2; > ($t, @ABC) »+=« (.01, dABC($t, @ABC, .01)) > ) { > printf "t = %.02f : %s\n", $t, @ABC.fmt("%+.3e"); > } > > > --- > > I'm having problem specially in the "multi infix" and even in the "norm" sub routine. The problem is that I do not understand the construction of these in Perl 5 (otherwise, I would translate this easely, and I wouldn't be asking for help...) > > Any help is apreciated. > > Clear skies > > Rui FernandesThread Next

**Re: Help with Perl 6 script**by William Michels via perl6-users- Re: Help with Perl 6 script by Eliza

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