Reviewer needed: 6282196 There should be Math.mod(number, modulo) methods (original) (raw)

Joe Darcy joe.darcy at oracle.com
Wed Apr 18 01:14:20 UTC 2012

On 04/17/2012 07:50 AM, Roger Riggs wrote:

I'm not sure have all the history around the Math vs StrictMath distinction.

For the more "interesting" mathematical methods where multiple implementations are reasonable, the StrictMath version provides cross-platform reproducibility by specifying the particular algorithm that is used while the Math class only specifies general quality of implementation criteria.

There are many cross references between Math and StrictMath for common functions, for example, ulp, getExponent, copySign, etc. The distinction is clearer for floating point operations than for int/log computations.

For operations where the Math and StrictMath siblings are specified to have the same output for all arguments, it is valid for either one to delegate to the other. It is always valid for Math.foo to be implemented as a call to StrictMath.foo, but the reverse is not always true.

Since the Math methods are probably called more often, if the Math and StrictMath methods are semantically equivalent, I'd recommend putting the real implementation in Math and having StrictMath do the call to its sibling.

Cheers,

-Joe

Roger

On 04/16/2012 05:27 PM, Alex Lam S.L. wrote: Hi there,

Sorry if this has been asked before, but I am curious as to why the newer methods in StrictMath (including addExact etc.) are now delegating to methods in Math. Looking at the other static methods, they seem to be going in the opposite direction, i.e. Math methods calling equivalent methods in StrictMath.

Thanks, Alex.

On Mon, Apr 16, 2012 at 10:08 PM, Roger Riggs<Roger.Riggs at oracle.com> wrote: Hi, I've corrected a number of issues raised with javadoc in java.lang.Math and java.lang.StrictMath. The updated webrev is: http://cr.openjdk.java.net/~rriggs/6282196.2/ Please review. Thanks, Roger

On 03/05/2012 08:38 AM, Roger Riggs wrote: CR 6282196 There should be Math.mod(number, modulo) methods http://bugs.sun.com/bugdatabase/viewbug.do?bugid=6282196 Requests that floor and modulus methods be provided for primitive types. Floor division is pretty straight-forward, rounding toward minus infinity. For modulus of int and long, the sign and range follow the exiting floor method in java.util.Math and satisfy the relation that mod(x, y) = (x - floorDiv(x, y) * y).

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