Calculation error

[supachaiofficial]

• Version:
  -> v4.8.1
  -> v7.8.0

• Platform:
  -> Linux ip-172-31-17-62 4.4.0-72-generic [stream] support piping multiple streams into a single stream #93-Ubuntu SMP Fri Mar 31 14:07:41 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
  -> Darwin supachai-macbook-pro.local 16.5.0 Darwin Kernel Version 16.5.0: Fri Mar 3 16:52:33 PST 2017; root:xnu-3789.51.2~3/RELEASE_X86_64 x86_64

Node Input:
console.log('print output: ',93.46+100.00+93.46)
Node Output:
print output: 286.91999999999996

Expect Correct Result:
print output: 286.92

[ChALkeR]

That is the expected behaviour per the ECMAScript spec, the binary numbers defined in IEEE 754-2008 behave that way.

[ChALkeR]

You can verify that in browser developers console (both Firefox and Chromium).

Also you can verify that in other languages, e.g. python.

With C++:

  double x = 93.46 + 100.00 + 93.46;
  std::cout << std::setprecision(20) << x << std::endl;

will give you 286.91999999999995907.

The only difference here is the default rounding of the output in C++ — to obtain similar results in JS, you would probably want to perform the rounding manually.

[supachaiofficial]

echo ("php calculation\n93.46+100.00+93.46 = ");
echo ( 93.46+100.00+93.46 );
echo ("\n");

will show:
php calculation
93.46+100.00+93.46 = 286.92

[ChALkeR]

@supachaiofficial That's rounding on the output (or, more specifically, on the default number-to-string conversion).

php > echo number_format(93.46+100.00+93.46, 15)."\n";
286.919999999999959

You could verify that it's the rounding on the output/conversion with a similar example:

php > echo 286.91999999999996 . "\n";
286.92