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grails how to check Double negative zero

I googled the answer. They said use Double.compare(). It does not work.

Double.compare(-0d, 0d) < 0

This gives me false. Should be true.

Math.signum() does not work with -0d. The document says it will give me back -0d.

On the other hand, if I have a formula that calculate the value to be -zero, compare gives me a different answer.

def xyz = -0d
Double.compare(xyz, 0d) < 0 will give me false

def xyz = 0d * -1d
Double.compare(xyz, 0d) < 0 will give me true

Is this a bug in Grails?

Solution

  • Why do you expect comparing -0d with 0d to be not equal?

    Double.compare(-0d, 0d) < 0// returns false

    cause

    Double.compare(-0d, 0d) == 0 //returns true