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authordave <dave@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2003-12-28 20:47:56 +0000
committerdave <dave@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2003-12-28 20:47:56 +0000
commit6cd63a70f6ecf416485261ee93c25c5f98879566 (patch)
treeeec9f1fc88d2ac95e3e40b9f3d10d0cc786d990c /random.c
parent9f5554aa5c341c259920afd01f745406af8ab270 (diff)
RDoc Struct and random
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@5340 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'random.c')
-rw-r--r--random.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/random.c b/random.c
index 86c8198..9a843f2 100644
--- a/random.c
+++ b/random.c
@@ -172,6 +172,20 @@ random_seed()
return tv.tv_sec ^ tv.tv_usec ^ getpid() ^ n++;
}
+/*
+ * call-seq:
+ * srand(number=0) => old_seed
+ *
+ * Seeds the pseudorandom number generator to the value of
+ * <i>number</i>.<code>to_i.abs</code>. If <i>number</i> is omitted
+ * or zero, seeds the generator using a combination of the time, the
+ * process id, and a sequence number. (This is also the behavior if
+ * <code>Kernel::rand</code> is called without previously calling
+ * <code>srand</code>, but without the sequence.) By setting the seed
+ * to a known value, scripts can be made deterministic during testing.
+ * The previous seed value is returned. Also see <code>Kernel::rand</code>.
+ */
+
static VALUE
rb_f_srand(argc, argv, obj)
int argc;
@@ -193,6 +207,26 @@ rb_f_srand(argc, argv, obj)
return ULONG2NUM(old);
}
+/*
+ * call-seq:
+ * rand(max=0) => number
+ *
+ * Converts <i>max</i> to an integer using max1 =
+ * max<code>.to_i.abs</code>. If the result is zero, returns a
+ * pseudorandom floating point number greater than or equal to 0.0 and
+ * less than 1.0. Otherwise, returns a pseudorandom integer greater
+ * than or equal to zero and less than max1. <code>Kernel::srand</code>
+ * may be used to ensure repeatable sequences of random numbers between
+ * different runs of the program. Ruby currently uses a modified
+ * Mersenne Twister with a period of 219937-1.
+ *
+ * srand 1234 #=> 0
+ * [ rand, rand ] #=> [0.191519450163469, 0.49766366626136]
+ * [ rand(10), rand(1000) ] #=> [6, 817]
+ * srand 1234 #=> 1234
+ * [ rand, rand ] #=> [0.191519450163469, 0.49766366626136]
+ */
+
static VALUE
rb_f_rand(argc, argv, obj)
int argc;