implementation of polymod method to play with

rakudo · Feb 14, 2015 · 874caf6 · 874caf6
1 parent 949b809
commit 874caf6
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Showing 2 changed files with 31 additions and 0 deletions.
diff --git a/src/core/Int.pm b/src/core/Int.pm
@@ -58,6 +58,22 @@ my class Int does Real { # declared in BOOTSTRAP
         nqp::p6box_s(nqp::base_I(self, $b)) ~ ($digits ?? '.' ~ '0' x $digits !! '');
     }
 
+    # If self is Int, we assume mods are Ints also.  (div fails otherwise.)
+    # If do-not-want, user should cast invocant to proper domain.
+    method polymod(Int:D: *@mods) {
+        my $more = self;
+        fail X::OutOfRange.new(what => 'invocant to polymod', got => $more, range => "0..*") if $more < 0;
+        gather {
+            for @mods -> $mod {
+                last unless $more;
+                fail X::Numeric::DivideByZero.new(using => 'polymod') unless $mod;
+                take $more mod $mod;
+                $more div= $mod;
+            }
+            take $more;
+        }
+    }
+
     method expmod(Int:D: Int:D \base, Int:D \mod) {
         nqp::expmod_I(self, nqp::decont(base), nqp::decont(mod), Int);
     }

diff --git a/src/core/Real.pm b/src/core/Real.pm
@@ -64,6 +64,21 @@ my role Real does Numeric {
     }
     method isNaN { Bool::False }
 
+    method polymod(Real:D: *@mods) {
+        my $more = self;
+        fail X::OutOfRange.new(what => 'invocant to polymod', got => $more, range => "0..*") if $more < 0;
+        gather {
+            for @mods -> $mod {
+                last unless $more;
+                fail X::Numeric::DivideByZero.new(using => 'polymod') unless $mod;
+                take my $rem = $more % $mod;
+                $more -= $rem;
+                $more /= $mod;
+            }
+            take $more;
+        }
+    }
+
     method base(Int:D $base, $digits = 1e8.log($base.Num).Int) {
         my Int $int_part = self.Int;
         my $frac = abs(self - $int_part);