[GitHub] [incubator-datasketches-java] leerho commented on a change in pull request #332: Relative error quantiles

[GitBox <gi...@apache.org>]

leerho commented on a change in pull request #332:
URL: https://github.com/apache/incubator-datasketches-java/pull/332#discussion_r518281624



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File path: src/main/java/org/apache/datasketches/Util.java
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@@ -380,6 +380,32 @@ public static boolean isMultipleOf8AndGT0(final long v) {
 
   //Powers of 2 related
 
+  /**
+   * Returns the number of one bits following the lowest-order ("rightmost") zero-bit in the
+   * two's complement binary representation of the specified long value, or 64 if the value is equal
+   * to minus one.
+   * @param v the value whose number of trailing ones is to be computed.
+   * @return the number of one bits following the lowest-order ("rightmost") zero-bit in the
+   * two's complement binary representation of the specified long value, or 64 if the value is equal
+   * to minus one.
+   */
+  public static int numberOfTrailingOnes(final long v) {
+    return Long.numberOfTrailingZeros(~v);
+  }
+
+  /**
+   * Returns the number of one bits preceding the highest-order ("leftmost") one-bit in the
+   * two's complement binary representation of the specified long value, or 64 if the value is equal
+   * to minus one.

Review comment:
       No.  Look at the Javadoc for java.lang.Long.numberOfTrailingZeros(long):
   "Returns the number of zero bits following the lowest-order ("rightmost") one-bit ...".  
   This is the complement of that, so the wording is:
   "Returns the number of one bits following the lowest-order ("rightmost") zero-bit ...".




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