A Bug in the SteemJs Regarding the Incorrect Reputation

justyy (84)in #programming • 6 years ago

Current SteemJs Library has a bug in computing the reputation. I have raised this two years ago and proposed a fix

Specifically:

console.log(steem.formatter.reputation(10004392664120));
console.log(steem.formatter.reputation(10004392664120+100000000000));

As you will see this output:

70
61

Which is incorrect. The problem is at the code L166

Here, the developer probably didn't know the Math.log10 function can be used to compute the Log10, instead, he/she uses a math trick Math.log(x)/Math.log(10) to compute the Math.log10 based on natural logarithm (base e ).

This will introduce rounding errors, and sometimes intermediate results will be amplified leading to much bigger errors.

console.log(Math.log10(1000))
console.log(Math.log(1000)/Math.log(10))

This will output

3
2.9999999999999996

In Line 168, it uses parseInt, therefore, the difference will be becoming ONE.

There are a few fixes:

change parseInt to Math.round
change entirely to use Math.log10
or completely rewriting this function, as my PR (approved by @ety001 thanks!, but not merged yet due to this is a legacy PR which was created more than 2 years ago and the main branch has differed a lot).
https://github.com/steemit/steem-js/pull/345/files

If you are happening to rely on this function, you probably need to do it yourself until this fix is merged.

Every little helps! I hope this helps!

Steem On!~

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