Largest difference between adjacent primes: Difference between revisions

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 Largest gap between primes up to   1000000:       114 between 492113 and 492227
 Largest gap between primes up to  10000000:       154 between 4652353 and 4652507
+</pre>
+=={{header|AWK}}==
+<lang AWK>
+# syntax: GAWK -f LARGEST_DIFFERENCE_BETWEEN_ADJACENT_PRIMES.AWK
+# converted from FreeBASIC
+BEGIN {
+    stop = 1000000
+    champi = 3
+    champj = 5
+    i = 5
+    record = 2
+    while (i < stop) {
+      j = next_prime(i)
+      if (j-i > record) {
+        champi = i
+        champj = j
+        record = j - i
+      }
+      i = j
+    }
+    printf("The largest difference between adjacent primes < %d is %d between %d and %d\n",stop,record,champi,champj)
+    exit(0)
+}
+function next_prime(n,  q) { # finds the next prime after n
+    if (n == 0) { return(2) }
+    if (n < 3) { return(++n) }
+    q = n + 2
+    while (!is_prime(q)) {
+      q += 2
+    }
+    return(q)
+}
+function is_prime(n,  d) {
+    d = 5
+    if (n < 2) { return(0) }
+    if (n % 2 == 0) { return(n == 2) }
+    if (n % 3 == 0) { return(n == 3) }
+    while (d*d <= n) {
+      if (n % d == 0) { return(0) }
+      d += 2
+      if (n % d == 0) { return(0) }
+      d += 4
+    }
+    return(1)
+}
+</lang>
+{{out}}
+<pre>
+The largest difference between adjacent primes < 1000000 is 114 between 492113 and 492227
 </pre>