FYI, planned update of floating-point terminology in JLS and JVMS to IEEE 754-2019

Joe Darcy joe.darcy at
Wed Apr 22 19:17:11 UTC 2020

Hi Florian,

On 4/22/2020 11:44 AM, Florian Weimer wrote:
> * Joe Darcy:
>> The Java Language Specification (JLS) and Java Virtual Machine
>> Specification (JVMS) use terminology from and make reference to the 1985
>> release of the IEEE 754 floating-point standard. The IEEE 754 standard
>> from 1985 has been superseded, most recently by a release from 2019.
> I don't have access to the IEEE standard (yeah, I know …), but there
> are rumors that the Math::min and Math::max implementations for
> floating point arguments now match some IEEE 754 operation.  If this
> indeed ttrue, it would make sense to update the Javadoc accordingly.
> (This goes in the opposite direction of what JDK-8240632 is about.)

One part of JDK-8240632 I'm considering is a table mapping between IEEE 
754-2019 operation/recommended operation and the Java math library 
equivalent. Many of them would be obvious, (sin -> sin, cos -> cos, 
etc.), but there are some that differ in their details.

Java Math.{min, max} have always specified the fine detail that -0.0 is 
treated as strictly less than +0.0 and that if either argument to 
min/max is a NaN, the result is also a NaN.

IEEE 754-2008 added minNum/maxNum operations. These did *not* require 
-0.0 to be treated as less than +0.0 and do not propagate a NaN value in 
case one argument is non-NaN.

IEEE 754-2019 added minimum/maximum operations that do correspond to the 
Java library definitions of min/max and updated minNum/maxNum to 
distinguish between signed zeros.



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