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Extension: arbitrary precision decimal arithmetic in PHP 7

php.internals

Rudi Theunissen

7 years ago
Hi everyone, I've been working on adding arbitrary precision decimal support as an alternative to *bcmath. *I have created an extension based on *mpdecimal*, which is what Python 3's decimal module is also based on. I haven't released or broadcast this project yet, because I wanted to discuss the API and implementation with internals first. See: https://github.com/php-decimal/php-decimal Any advice, commentary or objection is welcome. :) Thank you, Rudi Theunissen

Sara Golemon

7 years ago
On Fri, Sep 28, 2018 at 6:06 PM Rudi Theunissen <rtheunissen@php.net> wrote:
> I've been working on adding arbitrary precision decimal support as an > alternative to *bcmath. *I have created an extension based on *mpdecimal*, > which is what Python 3's decimal module is also based on. I haven't > released or broadcast this project yet, because I wanted to discuss the API > and implementation with internals first. >
Have you looked at GMPi ? https://github.com/sgolemon/gmpi It's a replacement for GMP (which includes floating point and an OOP interface). -Sara

Rudi Theunissen

7 years ago
Actually yes! You mentioned it to me 5 months ago in a thread on Reddit: https://www.reddit.com/r/PHP/comments/8fpwi4/if_php_had_a_native_decimal_type_would_you_use_it/dy6zon9/ I'll take a close look at GMPi today and compare them objectively. :) On Sat, Sep 29, 2018 at 7:20 AM Sara Golemon <pollita@php.net> wrote:

Albert Casademont Filella

7 years ago
Looks promising! Could it be added to PECL maybe? That would make it easier for people to test :D On Sat, 29 Sep 2018 at 17:46, Rudi Theunissen <rtheunissen@php.net> wrote:

Rudi Theunissen

7 years ago
Yes absolutely, I haven't written tests or documentation or a release plan yet though. I started working on this less than a week ago so just looking for feedback and validation from internals before I spend time wrapping it up. On Sat, Sep 29, 2018, 10:17 Albert Casademont <albertcasademont@gmail.com> wrote:

Rudi Theunissen

7 years ago
I wrote a basic benchmark and GMPi appears to be about twice as fast (+ and - ops) but produces a different result. GMPi was also running out of memory when attempting to apply multiply and divide operators. The benchmark only uses + and - now. I used bcmath for the reference value. If there's a bug we can solve here, rather than a fundamental accuracy issue, GMPi looks promising. 😊 See: https://gist.github.com/rtheunissen/973ea1719c02a4204dabfe9dffd78c4b On Sat, Sep 29, 2018, 07:20 Sara Golemon <pollita@php.net> wrote:

Rudi Theunissen

7 years ago
GNU MPFR looks solid too, significantly faster because it uses base 2 storage, but may have difficulty converting to decimal. I'll fork a version that uses mpfr instead of libmpdec and add it to the benchmark. I know using basic + and - isn't much of a benchmark but it's a start. I believe that many projects, especially in finance and science, can benefit from a fast, friendly, PHP 7+ decimal library. On Sat, Sep 29, 2018, 10:25 Rudi Theunissen <rtheunissen@php.net> wrote:

Rudi Theunissen

7 years ago
Hi everyone, I've made some good progress on this project and I would love for someone to review it for me? I want to learn as much as I can to produce something as good as possible. if you are curious to see it in action first, there is a sandbox here: http://php-decimal.io/#sandbox Source is here: https://github.com/php-decimal/extension Thank you. :) Rudi On Sat, Sep 29, 2018 at 10:45 AM Rudi Theunissen <rtheunissen@php.net> wrote: