RNG-55: Check for zero norm.
Project: http://git-wip-us.apache.org/repos/asf/commons-rng/repo Commit: http://git-wip-us.apache.org/repos/asf/commons-rng/commit/8539ccbe Tree: http://git-wip-us.apache.org/repos/asf/commons-rng/tree/8539ccbe Diff: http://git-wip-us.apache.org/repos/asf/commons-rng/diff/8539ccbe Branch: refs/heads/master Commit: 8539ccbeda3d390390cfc57185cfc6d2f6d0ebee Parents: c54506b Author: Gilles <er...@apache.org> Authored: Thu Aug 16 14:44:56 2018 +0200 Committer: Gilles <er...@apache.org> Committed: Thu Aug 16 14:44:56 2018 +0200 ---------------------------------------------------------------------- .../commons/rng/sampling/UnitSphereSampler.java | 9 +++++++++ .../rng/sampling/UnitSphereSamplerTest.java | 18 ++++++++++++++++++ src/changes/changes.xml | 3 +++ 3 files changed, 30 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/commons-rng/blob/8539ccbe/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/UnitSphereSampler.java ---------------------------------------------------------------------- diff --git a/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/UnitSphereSampler.java b/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/UnitSphereSampler.java index b289025..46dd474 100644 --- a/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/UnitSphereSampler.java +++ b/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/UnitSphereSampler.java @@ -59,6 +59,15 @@ public class UnitSphereSampler { normSq += comp * comp; } + if (normSq == 0) { + // Zero-norm vector is discarded. + // Using recursion as it is highly unlikely to generate more + // than a few such vectors. It also protects against infinite + // loop (in case a buggy generator is used), by eventually + // raising a "StackOverflowError". + return nextVector(); + } + final double f = 1 / Math.sqrt(normSq); for (int i = 0; i < dimension; i++) { v[i] *= f; http://git-wip-us.apache.org/repos/asf/commons-rng/blob/8539ccbe/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/UnitSphereSamplerTest.java ---------------------------------------------------------------------- diff --git a/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/UnitSphereSamplerTest.java b/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/UnitSphereSamplerTest.java index a66e4cd..2b7ff47 100644 --- a/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/UnitSphereSamplerTest.java +++ b/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/UnitSphereSamplerTest.java @@ -56,6 +56,24 @@ public class UnitSphereSamplerTest { } } + /** Cf. RNG-55. */ + @Test(expected = StackOverflowError.class) + public void testBadProvider1() { + final UniformRandomProvider bad = new UniformRandomProvider() { + public long nextLong(long n) { return 0; } + public long nextLong() { return 0; } + public int nextInt(int n) { return 0; } + public int nextInt() { return 0; } + public float nextFloat() { return 0; } + public double nextDouble() { return 0;} + public void nextBytes(byte[] bytes, int start, int len) {} + public void nextBytes(byte[] bytes) {} + public boolean nextBoolean() { return false; } + }; + + new UnitSphereSampler(1, bad).nextVector(); + } + /** * @return the length (L2-norm) of given vector. */ http://git-wip-us.apache.org/repos/asf/commons-rng/blob/8539ccbe/src/changes/changes.xml ---------------------------------------------------------------------- diff --git a/src/changes/changes.xml b/src/changes/changes.xml index f36c4e3..2bd1a44 100644 --- a/src/changes/changes.xml +++ b/src/changes/changes.xml @@ -67,6 +67,9 @@ Additional code is provided in the following module: It is however not part of the official API and no compatibility should be expected in subsequent releases. "> + <action dev="erans" type="fix" issue="RNG-55" due-to="Alex D. Herbert"> + "UnitSphereSampler": Prevent returning NaN components. + </action> </release> <release version="1.1" date="2018-08-14" description="
