Category talk:Wren-math: Difference between revisions

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@@ Line 230: / Line 230: @@
         if (a.count == 2) return l
         return lcm(a[2..-1] + [l])
+    }
+    // Private helper method for modMul method.
+    static checkedAdd_(a, b, c) {
+        var room = c - 1 - a
+        if (b <= room) {
+            a = a + b
+        } else {
+            a = b - room - 1
+        }
+        return a
     }
@@ Line 237: / Line 248: @@
         var sign = x.sign * n.sign
         var z = 0
-        x = x.abs
-        n = n.abs
         m = m.abs
+        x = x.abs % m
+        n = n.abs % m
+        if (n > x) {
+            var t = x
+            x = n
+            n = t
+        }
         while (n > 0) {
-            if (n % 2 == 1) z = (z + x) % m
+            if (n % 2 == 1) z = checkedAdd_(z, x, m)
-            x = (x * 2) % m
+            x = checkedAdd_(x, x, m)
             n = div(n, 2)
         }
@@ Line 349: / Line 365: @@
     }
-    // Returns true if the current instance is prime, false otherwise but uses the
+    // Returns true if 'n' is prime, false otherwise but uses the
-    // Miller-Rabin test which should be faster for checking isolated larger integers.
+    // Miller-Rabin test which should be faster for 'n' >= 2 ^ 32.
     static isPrime2(n) {
         if (!n.isInteger || n < 2) return false
@@ Line 417: / Line 433: @@
         while (true) {
             if (Int.isPrime(n)) return n
+            n = n + 2
+        }
+    }
+    // As 'nextPrime' method but uses 'isPrime2' rather than 'isPrime'.
+    // Should be faster for 'n' >= 2 ^ 32.
+    static nextPrime2(n) {
+        if (n < 2) return 2
+        n = (n%2 == 0) ? n + 1 : n + 2
+        while (true) {
+            if (Int.isPrime2(n)) return n
             n = n + 2
         }