X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;f=ucw%2Fprime.h;h=87d13f92ed4fe285ae3925a411bd90b0e609b83c;hb=634be141f3f014e31d5931a968c0c0f7e07205fb;hp=9ca2a01ebce72d48c2cdf878c8dc5d2e46ef2f87;hpb=689b60e4c61d300b576fdb7007de51189d2f0f7e;p=libucw.git

diff --git a/ucw/prime.h b/ucw/prime.h
index 9ca2a01e..87d13f92 100644
--- a/ucw/prime.h
+++ b/ucw/prime.h
@@ -21,12 +21,32 @@
 
 /* prime.c */
 
+/**
+ * Return a non-zero value iff @x is a prime number.
+ * The time complexity is `O(sqrt(x))`.
+ **/
 int isprime(uns x);
+
+/**
+ * Return some prime greater than @x. The function does not checks overflows, but it should
+ * be safe at least for @x lower than `1U << 31`.
+ * If the Cramer's conjecture is true, it should have complexity `O(sqrt(x) * log(x)^2)`.
+ **/
 uns nextprime(uns x);
 
 /* primetable.c */
 
+/**
+ * Quickly lookup a precomputed table to return a prime number greater than @x.
+ * Returns zero if there is no such prime (we guarantee the existance of at
+ * least one prime greater than `1U << 31` in the table).
+ **/
 uns next_table_prime(uns x);
+
+/**
+ * Quickly lookup a precomputed table to return a prime number smaller than @x.
+ * Returns zero if @x is smaller than `7`.
+ **/
 uns prev_table_prime(uns x);
 
 #endif // _UCW_PRIME_H