# PSA: floating-point arithmetic

**URL:** https://discourse.julialang.org/t/psa-floating-point-arithmetic/8678
**Category:** Offtopic
**Created:** [January 29, 2018, 7:56pm UTC](https://discourse.julialang.org/t/psa-floating-point-arithmetic/8678 "2018-01-29T19:56:38Z")
**Posts on this page:** 1
**Showing post:** 7

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### Author: ![foobar\_lv2](https://avatars.discourse-cdn.com/v4/letter/f/ee59a6/32.png) [@foobar\_lv2](https://discourse.julialang.org/u/foobar_lv2)
#### Post date: [January 31, 2018, 9:49pm UTC](https://discourse.julialang.org/t/psa-floating-point-arithmetic/8678/7 "2018-01-31T21:49:12Z")

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Somewhat naive question: There is this horrible horrible x86 extended precision. Does julia ever use this?

See e.g. [http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/](http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/), [http://www.exploringbinary.com/why-volatile-fixes-the-2-2250738585072011e-308-bug/](http://www.exploringbinary.com/why-volatile-fixes-the-2-2250738585072011e-308-bug/). Is there anything I need to do to be safe from this? I have never seen julia emit the 80 bit stuff; I guess it is never used, but I’d be happy about reassurance.

Context: I have a pure inlined float function; I need it to reliably produce identical outputs, regardless of context where it is inlined in (and I already make sure that I never use it from a` @fastmath` context).

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