webrev: http://cr.openjdk.java.net/~pbansal/8220811/webrev02/
Regards,
Pankaj
-----Original Message-----
From: Volodin, Vladislav <vladislav.volo...@sap.com>
Sent: Sunday, March 15, 2020 2:03 AM
To: Pankaj Bansal <pankaj.b.ban...@oracle.com>
Cc: swing-dev@openjdk.java.net; Jason Mehrens
<jason_mehr...@hotmail.com>; Sergey Bylokhov
<sergey.bylok...@oracle.com>; Alexey Ivanov <alexey.iva...@oracle.com>
Subject: Re: <Swing Dev> [15] RFR JDK-8220811: SpinnerNumberModel
floating point rounding issue
Hello Pankaj,
I am not the reviewer, but I agree with Jason. To me
p1.equals(Double.NaN) looks confusing. Because people might think
that it will be equivalent to p1 == Double.NaN, that will return
false, when p1 is also NaN
(https://urldefense.com/v3/__https://stackoverflow.com/questions/8819738/why-does-double-nan-double-nan-return-false__;!!GqivPVa7Brio!MCTIuSS1NcMZWK7ZWOAVUhgC-AoVMYwCGbgTiDOH5pO2PQfW7b7XN-hLRtqBuhi6XnVl$
).
I prefer to use the dedicated method such as "public static boolean
isNaN(double v)". It looks self-descriptive.
Meanwhile, I remember you sentence regarding the number of steps:
> double min=-.15,max=0.15,stepsize=.05, the steps is
calculated as 5. double min=-.15,max=0.20,stepsize=.05, the steps is
calculated as 7 instead of 6.
I checked this part with the code:
Double min = -.15;
Double max = 0.15;
Double stepsize = .05;
Double steps = (max - min) / stepsize;
And I found out that in this case the number of steps will be
5,999999....., but we can compensate it with either Math.round, it
will return 6, or we can add the "epsilon" value to "max", and count
the number of steps as it is:
Double max = 0.15 + Math.ulp(1.0); Steps count will be
6.00000238418579.
Since there is no value in Double (and probably float) less than
Math.ulp (or epsilon, if we use this term), it will be probably safe
to use my approach. What do you think?
Kind regards,
Vlad
On 14.03.20, 15:51, "Pankaj Bansal" <pankaj.b.ban...@oracle.com>
wrote:
Hello Jason,
<< I would assume newMinimum.equals(Double.NaN) and
newMinimum.equals(Float.NaN) should always evaluate to false.
It seems to work as expected.
Double p1 = Double.NaN;
Double p2 = 1.0;
System.out.println(p1.equals(Double.NaN)); //prints true
System.out.println(p2.equals(Double.NaN)); //prints false
Regards,
Pankaj
-----Original Message-----
From: Jason Mehrens <jason_mehr...@hotmail.com>
Sent: Saturday, March 14, 2020 8:09 PM
To: Pankaj Bansal <pankaj.b.ban...@oracle.com>; Sergey
Bylokhov <sergey.bylok...@oracle.com>; Alexey Ivanov
<alexey.iva...@oracle.com>; Volodin, Vladislav
<vladislav.volo...@sap.com>
Cc: swing-dev@openjdk.java.net
Subject: Re: <Swing Dev> [15] RFR JDK-8220811: SpinnerNumberModel
floating point rounding issue
Pankaj,
I would assume newMinimum.equals(Double.NaN) and
newMinimum.equals(Float.NaN) should always evaluate to false.
Perhaps you want to use Float.isNaN and Double.isNaN instead?
Jason
________________________________________
From: swing-dev <swing-dev-boun...@openjdk.java.net> on behalf
of Pankaj Bansal <pankaj.b.ban...@oracle.com>
Sent: Saturday, March 14, 2020 8:11 AM
To: Sergey Bylokhov; Alexey Ivanov; Volodin, Vladislav
Cc: swing-dev@openjdk.java.net
Subject: Re: <Swing Dev> [15] RFR JDK-8220811: SpinnerNumberModel
floating point rounding issue
Hello Sergey,
<< It will differ for two cases:
- The error will not be accumulated when the counter will
move forward/backward, currently the result might different on each
iteration.
- Initial/Default value will never be skipped due to counter=0
I tried to code according to my understanding of the
idea. I have created a preliminary webrev to demonstrate what I am
doing. This is nowhere final, so please ignore the optimizations.
Please have a look.
As I was thinking, the precision error is creating issue while
creating the step count. I have to do lot of stuff to allow values
to be changed by editing the textfield. There are some other issues
also, like the double value is formatted according to the formatter
and that is also causing problems.
webrev:
http://cr.openjdk.java.net/~pbansal/8220811/webrev01/
Regards,
Pankaj
-----Original Message-----
From: Sergey Bylokhov
Sent: Wednesday, March 11, 2020 5:33 AM
To: Pankaj Bansal <pankaj.b.ban...@oracle.com>; Alexey Ivanov
<alexey.iva...@oracle.com>; Volodin, Vladislav
<vladislav.volo...@sap.com>
Cc: swing-dev@openjdk.java.net
Subject: Re: <Swing Dev> [15] RFR JDK-8220811: SpinnerNumberModel
floating point rounding issue
On 3/10/20 5:34 am, Pankaj Bansal wrote:
> Hello Sergey/Vlad/Alexey,
>
> Sorry, I could not reply to this earlier. I have one doubt
about this approach. Won't the calculation of stepCount itself
suffer from floating point issue? I mean the user will pass min,
max, stepsize, then wont the calculation of steps required to go
from min to max will also suffer from same floating point issue? I
think there can be an rounding of error of -1 or +1 in calculation
of step count.
It will differ for two cases:
- The error will not be accumulated when the counter will
move forward/backward, currently the result might different on each
iteration.
- Initial/Default value will never be skipped due to counter=0
>
> eg.
>
> int steps =0;
>
> for (double i=min+stepsize; i<=max; i+=stepsize)
> steps++;
>
> double min=-.15,max=0.15,stepsize=.05, the steps is
calculated as 5. double min=-.15,max=0.20,stepsize=.05, the steps is
calculated as 7 instead of 6.
>
>
> The reason is that, there is floating point error in first
case, but it is not present in second case.
>
> I think the best we can do here is as Sergey suggested in
his first
> reply to use Math.fma to reduce the floating point error
chances from
> 2 to 1 or just close this as not an issue
>
> Regards,
>
> Pankaj
>
>
> On 19/02/20 3:49 AM, Sergey Bylokhov wrote:
>> I think it should work, the step will counts from the
default value.
>>
>> So currently:
>> 1. if the user set default value to X1 and then he iterates
forward 100 times then he will get some X2. During this calculation,
he could get "100" rounding issues.
>> 2. If later the user decides iterates backward then most
probably he will not get X1, and the amount of possible "rounding
issues" will be 200.
>>
>> If the user will repeat steps 1. and 2. then each time the
values will "float".
>>
>> If we will use counter then in the worst case we will get
only two roundings per step: X1+step*100 = X2(if we will use fma we
will get only one for every step).
>>
>> It will not solve all issues but at least will make the
iteration "stable".
>>
>> On 2/17/20 1:59 am, Alexey Ivanov wrote:
>>> Hi Vlad,
>>>
>>> The idea looks reasonable. However, it does not allow for
manual editing. The cases where max and min values are not multiples
of step would be hard to handle with this approach. For example: max
= 10.05, min = 0.01, step = 0.1; how many ticks are there? What if
the user enters 1.01015; the value should change to 1.11015 or 0.91015.
>>>
>>> On 13/02/2020 22:22, Volodin, Vladislav wrote:
>>>> Hello Sergey, Alexey and Pankaj,
>>>>
>>>> I am reading the current discussion and I was thinking
about an idea changing the code in the way that instead of working
with float/double numbers we work with integer ticks. For example,
the model remembers the min/max/step values and calculates a number
of steps required to reach from min to max. All increment/decrement
actions are done against the current ˋtickˋ value. If the current
ˋtickˋ reaches 0 - we return min; if maxTick — we return max. And
the current value can be always counted as (min + tick * step) if
tick is neither zero, nor max tick count.
>>>>
>>>> At least if we deal with integer ticks, but all reading
operations calculate on the fly, we will be able to control the
representativeness of output.
>>>>
>>>> As always, I don’t know all the details and possible
consequences, so feel free to ignore my email, if I am wrong.
>>>>
>>>> Kind regards,
>>>> Vlad
>>>>
>>>> Sent from myPad
>>>>
>>>>> On 13. Feb 2020, at 22:34, Sergey Bylokhov
<sergey.bylok...@oracle.com> wrote:
>>>>>
>>>>> On 2/12/20 8:21 am, Alexey Ivanov wrote:
>>>>>> The bug report says that going from -0.15 to -0.10 does
not allow going back to -0.15. This happens because the result of
this sequence of operations cannot be represented exactly, or, in
other words, because of rounding errors; or rather the result is
less than the set minimal value.
>>>>>> Can we set the value of the spinner to the set minimal
value instead of disallowing the operation. I mean, after going up
the displayed value is -0.10; going down by 0.05 gives the result
which is less than the minimal value for the spinner, and thus going
down is not allowed. What if we set the value of the spinner to its
minimal value instead?
>>>>> In this case, we will need to update all types including
int.
>>>>> Isn't it will be surprised that the spinner will show
the value which is not calculated as "defaultValue + stepValue *
stepCount"?
>>>>>
>>>>>
>>>>> --
>>>>> Best regards, Sergey.
>>
>>
>
--
Best regards, Sergey.
