MATH-1383 Update userguide: removing reference to deleted package "o.a.c.math4.rng".
Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo Commit: http://git-wip-us.apache.org/repos/asf/commons-math/commit/d52a020e Tree: http://git-wip-us.apache.org/repos/asf/commons-math/tree/d52a020e Diff: http://git-wip-us.apache.org/repos/asf/commons-math/diff/d52a020e Branch: refs/heads/master Commit: d52a020ef7bdc98ba2ba88a8e2bdd412d30a930c Parents: e2423a4 Author: Gilles <gil...@harfang.homelinux.org> Authored: Sun Aug 28 00:06:51 2016 +0200 Committer: Gilles <gil...@harfang.homelinux.org> Committed: Sun Aug 28 00:06:51 2016 +0200 ---------------------------------------------------------------------- src/site/site.xml | 1 - src/site/xdoc/userguide/random.xml | 45 +++++++++++++-------------------- 2 files changed, 18 insertions(+), 28 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/commons-math/blob/d52a020e/src/site/site.xml ---------------------------------------------------------------------- diff --git a/src/site/site.xml b/src/site/site.xml index 22fefe6..b6e0f7a 100644 --- a/src/site/site.xml +++ b/src/site/site.xml @@ -76,7 +76,6 @@ <item name="Filters" href="/userguide/filter.html"/> <item name="Machine Learning" href="/userguide/ml.html"/> <item name="Exceptions" href="/userguide/exceptions.html"/> - <item name="Random Number Generators" href="/userguide/rng.html"/> </menu> <head> http://git-wip-us.apache.org/repos/asf/commons-math/blob/d52a020e/src/site/xdoc/userguide/random.xml ---------------------------------------------------------------------- diff --git a/src/site/xdoc/userguide/random.xml b/src/site/xdoc/userguide/random.xml index 8ef9f84..868c96a 100644 --- a/src/site/xdoc/userguide/random.xml +++ b/src/site/xdoc/userguide/random.xml @@ -49,14 +49,8 @@ These utilities rely on an underlying "source of randomness", which in most cases is a pseudo-random number generator (PRNG) that produces sequences of numbers that are uniformly distributed within their range. - Commons Math provides many PRNG implementations that share a common - interface: - <a href="../apidocs/org/apache/commons/math4/rng/UniformRandomProvider.html"> - UniformRandomProvider</a> (for more details about this interface and the - available RNG algorithms, please refer to the Javadoc of package - <a href="../apidocs/org/apache/commons/math4/rng/package-summary.html"> - org.apache.commons.math4.rng</a> and <a href="../userguide/rng.html">this section</a> - of the userguide. + Commons Math depends on <a href="http://commons.apache.org/rng";>Commons Rng</a> + for the PRNG implementations. </p> <p> A PRNG algorithm is often deterministic, i.e. it produces the same sequence @@ -96,23 +90,20 @@ <dd> It is possible for a sequence of numbers to appear random, but nonetheless to be predictable based on the algorithm used to generate the - sequence. If in addition to randomness, strong unpredictability is - required, it is best to use a + sequence. + When in addition to randomness, strong unpredictability is + required, a <a href="http://www.wikipedia.org/wiki/Cryptographically_secure_pseudo-random_number_generator";> - secure random number generator</a> to generate values (or strings). - - Most PRNG implemented in this library are not secure in that sense, except - perhaps the <a href="../apidocs/org/apache/commons/math4/rng/internal/source32/ISAACRandom.html"> - ISAAC generator</a>. - An alternative is to use an instance of the JDK-provided <code>SecureRandom</code> - generator. + secure random number generator</a> + should be used to generate values (or strings), for example an instance of + the JDK-provided <code>SecureRandom</code> generator. In general, such secure generator produce sequence based on a source of true randomness, and sequences started with the same seed will diverge. The <a href="../apidocs/org/apache/commons/math4/random/RandomUtils.html">RandomUtils</a> - class provides a "factory" method to wrap <code>java.util.Random</code> or - <code>java.security.SecureRandom</code> instances in an object that implements - the <a href="../apidocs/org/apache/commons/math4/rng/UniformRandomProvider.html"> + class provides a method for wrapping a <code>java.util.Random</code> or + <code>java.security.SecureRandom</code> instance in an object that implements + the <a href="http://commons.apache.org/proper/commons-rng/apidocs/org/apache/commons/rng/UniformRandomProvider.html";> UniformRandomProvider</a> interface: <source> UniformRandomProvider rg = RandomUtils.asUniformRandomProvider(new java.security.SecureRandom()); @@ -151,21 +142,21 @@ UniformRandomProvider rg = RandomUtils.asUniformRandomProvider(new java.security <dt>Generating random vectors from a bivariate normal distribution</dt><dd> <source> // Import common PRNG interface and factory class that instantiates the PRNG. -import org.apache.commons.math4.rng.UniformRandomProvider; -import org.apache.commons.math4.rng.RandomSource; +import org.apache.commons.rng.UniformRandomProvider; +import org.apache.commons.rng.RandomSource; -// Create (and possibly seed) a PRNG (could use any of the CM-provided generators) +// Create (and possibly seed) a PRNG (could use any of the CM-provided generators). long seed = 17399225432L; // Fixed seed means same results every time UniformRandomProvider rg = RandomSource.create(RandomSource.MT, seed); -// Create a GassianRandomGenerator using rg as its source of randomness +// Create a GaussianRandomGenerator using "rg" as its source of randomness. GaussianRandomGenerator rawGenerator = new GaussianRandomGenerator(rg); -// Create a CorrelatedRandomVectorGenerator using rawGenerator for the components +// Create a CorrelatedRandomVectorGenerator using "rawGenerator" for the components. CorrelatedRandomVectorGenerator generator = new CorrelatedRandomVectorGenerator(mean, covariance, 1.0e-12 * covariance.getNorm(), rawGenerator); -// Use the generator to generate correlated vectors +// Use the generator to generate correlated vectors. double[] randomVector = generator.nextVector(); ... </source> @@ -181,7 +172,7 @@ double[] randomVector = generator.nextVector(); double[] mean = {1, 2}; double[][] cov = {{9, c}, {c, 16}}; RealMatrix covariance = MatrixUtils.createRealMatrix(cov); </source> - where c is the desired covariance. If you are starting with a desired correlation, + where "c" is the desired covariance. If you are starting with a desired correlation, you need to translate this to a covariance by multiplying it by the product of the standard deviations. For example, if you want to generate data that will give Pearson's R of 0.5, you would use c = 3 * 4 * 0.5 = 6.
