[MATH-1196] FastMath.round (like Math.round) returns surprising results for some arguments

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4.1
• Fix Version/s: 4.0
• Assignee: Unassigned
• Reporter: Phil Steitz
• Created: 17/Jan/15 17:51
• Updated: 05/Aug/16 21:04
• Resolved: 05/Aug/16 21:04

Description

The first assertion in the test case below succeeds, but the second fails

 /*
     * http://bugs.java.com/bugdatabase/view_bug.do?bug_id=6430675
     */
    @Test
    public void testRoundDown() {
        final double x = 0x1.fffffffffffffp-2;
        Assert.assertTrue(x < 0.5d);
        Assert.assertEquals(0, FastMath.round(x));
    }

This is being tracked as a JDK (actually spec) bug here:
http://bugs.java.com/bugdatabase/view_bug.do?bug_id=6430675