Float type does not follow IEEE 754 standard

[drewtownchi]

Elasticsearch version 6.0.0

Plugins installed: [x-pack]

JVM version (java -version): 1.8.0_60

OS version (uname -a if on a Unix-like system): Centos 7

Description of the problem including expected versus actual behavior:

https://www.elastic.co/guide/en/elasticsearch/reference/6.0/number.html
float | A single-precision 32-bit IEEE 754 floating point.

https://en.wikipedia.org/wiki/IEEE_754 "As with IEEE 754-1985, the biased-exponent field is filled with all 1 bits to indicate either infinity (trailing significand field = 0) or a NaN (trailing significand field ≠ 0)."

Elasticsearch is rejecting our infinity value floats. The Elasticsearch documentation claims to follow the IEEE 754 float spec but is rejecting infinity and NaN values.

Steps to reproduce:

1. This is the commit that changed this behavior d8ff6e9
2. Create an index
3. Send a finite float to a field on the index
4. Send an infinity value to the same field on the index

Provide logs (if relevant):
"caused_by"=>{"type"=>"illegal_argument_exception", "reason"=>"[float] supports only finite values, but got [Infinity]"}

[rjernst]

This is by design. Json has no way to represent inifinity or NaN.
See the original issue: #25534

[drewtownchi]

@rjernst Should the documentation be updated to say it follows RFC 4627 or ECMA-262 instead of IEEE 754? The Elasticsearch docs don't accurately reflect the accepted values for float/half-float/double

NOTE 4: Finite numbers are stringified as if by calling ToString(number). NaN and Infinity regardless of sign are represented as the String null.

[rjernst]

I'll reopen as a docs issue, but I'm not sure in what way we should change the docs. /cc @jpountz

[jpountz]

@drw112 would something like that work for you: A single-precision 32-bit IEEE 754 floating point, restricted to finite values.?

[drewtownchi]

Yes, I think that is clear and concise. Thanks!