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authorKenji Rikitake <[email protected]>2016-11-04 14:53:10 +0900
committerKenji Rikitake <[email protected]>2016-11-14 19:37:16 +0900
commitff568b5e818d04048009926a7fa2ea537d2e656d (patch)
treeea303d975cb356a80f093f24893bd10d69bc49f3 /lib/stdlib/doc/src
parentfc020db74ae4a27ee0b64251a29fdf306f1f4e5d (diff)
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Add jump functions to rand module
Jump functions returns the state after performing jump calculation to a rand module internal state, which is equivalent to perform a large number of calls of calculating new states for XorShift*/+ algorithms. This commit add jump functions for exsplus and exs1024 algorithms, and a wrapper function jump/1. The wrapper function will cause error with reason "not_implemented" if the jump function for the algorithm is not implemented. This commit adds following new functionalities: - Add new functions rand:jump/0 and rand:jump/1 - Add the member jump to type alg_handler(), a fun for performing the jump function - Add jump functions for exsplus, equivalent to 2^64 calls - Add jump functions for exs1024, equivalent to 2^512 calls - Revise seed_put/1, seed/1, seed/2 See <https://github.com/erlang/otp/pull/1235#discussion_r86950557> - Add dummy jump function for exs64 calling erlang:error(not_implemented) - Add jump function test cases as follows: * Add Common Test group reference_jump * Add tests for jump/0 to reference_jump_procdict/1 * Rename tests for jump/1 to reference_jump_state/1 * Rename gen_jump/1 to gen_jump_1/1 * Add Common Tests reference_jump_procdict and reference_jump_state to the group reference_jump - Add jump function documentation This commit also changes the Copyright year for Kenji Rikitake's code from 2015 to 2015-2016.
Diffstat (limited to 'lib/stdlib/doc/src')
-rw-r--r--lib/stdlib/doc/src/rand.xml35
1 files changed, 35 insertions, 0 deletions
diff --git a/lib/stdlib/doc/src/rand.xml b/lib/stdlib/doc/src/rand.xml
index 1dcc3de000..1364a3277b 100644
--- a/lib/stdlib/doc/src/rand.xml
+++ b/lib/stdlib/doc/src/rand.xml
@@ -41,6 +41,11 @@
Sebastiano Vigna</url>. The normal distribution algorithm uses the
<url href="http://www.jstatsoft.org/v05/i08">Ziggurat Method by Marsaglia
and Tsang</url>.</p>
+ <p>For some algorithms, jump functions are provided for generating
+ non-overlapping sequences for parallel computations.
+ The jump functions perform calculations
+ equivalent to perform a large number of repeated calls
+ for calculating new states. </p>
<p>The following algorithms are provided:</p>
@@ -48,14 +53,17 @@
<tag><c>exsplus</c></tag>
<item>
<p>Xorshift116+, 58 bits precision and period of 2^116-1</p>
+ <p>Jump function: equivalent to 2^64 calls</p>
</item>
<tag><c>exs64</c></tag>
<item>
<p>Xorshift64*, 64 bits precision and a period of 2^64-1</p>
+ <p>Jump function: not available</p>
</item>
<tag><c>exs1024</c></tag>
<item>
<p>Xorshift1024*, 64 bits precision and a period of 2^1024-1</p>
+ <p>Jump function: equivalent to 2^512 calls</p>
</item>
</taglist>
@@ -156,6 +164,33 @@ S0 = rand:seed_s(exsplus),
</func>
<func>
+ <name name="jump" arity="0"/>
+ <fsummary>Return the seed after performing jump calculation
+ to the state in the process dictionary.</fsummary>
+ <desc><marker id="jump-0" />
+ <p>Returns the state
+ after performing jump calculation
+ to the state in the process dictionary.</p>
+ <p>This function generates a <c>not_implemented</c> error exception
+ when the jump function is not implemented for
+ the algorithm specified in the state
+ in the process dictionary.</p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="jump" arity="1"/>
+ <fsummary>Return the seed after performing jump calculation.</fsummary>
+ <desc><marker id="jump-1" />
+ <p>Returns the state after performing jump calculation
+ to the given state. </p>
+ <p>This function generates a <c>not_implemented</c> error exception
+ when the jump function is not implemented for
+ the algorithm specified in the state.</p>
+ </desc>
+ </func>
+
+ <func>
<name name="normal" arity="0"/>
<fsummary>Return a standard normal distributed random float.</fsummary>
<desc>