AvgOf produces overflow for large values

[vmotsak]

new AvgOf(
          new ListOf<>(Double.MAX_VALUE, Double.MAX_VALUE).toArray(new Double[2])
).doubleValue();

returns an Infinity but should be Double.MAX_VALUE

[0crat]

@yegor256 please, pay attention to this issue

[yegor256]

@vmotsak definitely a bug, thanks for reporting (although, I have no idea how this can be fixed)

[0crat]

Job gh:yegor256/cactoos#532 is now in scope, role is DEV.

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Job gh:yegor256/cactoos#532 assigned to @allanws (DEV). The budget is fixed and it is 30 minutes. Please, read §4, §8, and §9. If the task is not clear, read this and this.

[svendiedrichsen]

@yegor256 i suppose you will have to use BigInteger/BigDecimal for your computations. Having the usual performance impact surely. But if performance is not key here this would have the highest accuracy.

[vmotsak]

This can be fixed by calculating the mean value, something like

double mean(Double[] ary) {
        double avg = 0;
        int t = 1;
        for (double x : ary) {
            avg += (x - avg) / t;
            ++t;
        }
        return avg;
    }

[svendiedrichsen]

Mathematically correct but you might run into strange double precision problems though. Probably not with your example but to have AvgOf work consistently correct you have to go with the highest precision.
See for i.e.

• http://bloodredsun.com/2011/06/22/doubles-financial-calculations/
• http://www.drdobbs.com/jvm/javas-floating-point-imprecision/240168744

about this. There is way more mathematically advanced stuff about this out there.

[svendiedrichsen]

Please see the average of new Double[]{100.0, 100.266} using the above mentioned mean method. Should be 100.133 of course. But it isn't. It is 100.13300000000001.

Another one: System.out.println(100.266 - 100.0);
Output: 0.26600000000000534

[svendiedrichsen]

@yegor256 : I have created an example of what IMO could be done with the AvgOf code to fix number overflow, fix precisions problem and cut some code repetitions. Please have a look here: svendiedrichsen@358b7f1

It is still not the most elegant piece of code and surely deserves some more refactoring. But i think it is better than before.

[0crat]

@allanws this job was assigned to you 5 days ago. It will be taken away from you soon, unless you close it, see §8. Read this and this, please.

[0crat]

@AllanWS/z this job was assigned to you 8 days ago. It will be taken away from you soon, unless you close it, see §8. Read this and this, please.

[allanwsilva]

@yegor256 please have a look at my latest comment on this issue.

[allanwsilva]

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@AllanWS The impediment was registered successfully

[yegor256]

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@yegor256 Job #532 is not assigned, can't put it on hold

[yegor256]

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[yegor256]

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@yegor256 This is what I know about this job, as in §32:

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[yegor256]

@0crat assign @AllanWS

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@yegor256 The job #532 assigned to @AllanWS/z. The budget is 30 minutes, see §4. Please, read §8 and §9. If the task is not clear, read this and this. @AllanWS/z is not a member of this project yet, but they can request to join. Check your profile and follow the instructions.

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Manual assignment of issues is discouraged, see §19: -5 points just awarded to @yegor256/z, total is +7780

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[fabriciofx]

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@fabriciofx This is what I know about this job, as in §32:

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The job #532 assigned to @rexim/z. The budget is 30 minutes, see §4. Please, read §8 and §9. If the task is not clear, read this and this.

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Order was successfully finished: +30 points just awarded to @rexim/z, total is +45

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The job #532 is now out of scope

[g4s8]

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@g4s8 This is what I know about this job, as in §32:

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