diff options
Diffstat (limited to 'graphx')
| -rw-r--r-- | graphx/src/main/scala/org/apache/spark/graphx/util/GraphGenerators.scala | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/graphx/src/main/scala/org/apache/spark/graphx/util/GraphGenerators.scala b/graphx/src/main/scala/org/apache/spark/graphx/util/GraphGenerators.scala index 635514f09e..60149548ab 100644 --- a/graphx/src/main/scala/org/apache/spark/graphx/util/GraphGenerators.scala +++ b/graphx/src/main/scala/org/apache/spark/graphx/util/GraphGenerators.scala @@ -100,8 +100,10 @@ object GraphGenerators { */ private def sampleLogNormal(mu: Double, sigma: Double, maxVal: Int): Int = { val rand = new Random() - val m = math.exp(mu + (sigma * sigma) / 2.0) - val s = math.sqrt((math.exp(sigma*sigma) - 1) * math.exp(2*mu + sigma*sigma)) + val sigmaSq = sigma * sigma + val m = math.exp(mu + sigmaSq / 2.0) + // expm1 is exp(m)-1 with better accuracy for tiny m + val s = math.sqrt(math.expm1(sigmaSq) * math.exp(2*mu + sigmaSq)) // Z ~ N(0, 1) var X: Double = maxVal |