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August 8, 2019 20:07Subject:

Help with Perl 6 scriptMessage ID:

CAFXK4YevvSWZ+SAxCgLP1_7GRLQ1VXZdZbvbCg60Q12-URyZVA@mail.gmail.comGreetings 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 Fernandes

**Help with Perl 6 script**by Rui Fernandes

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