Issue #21308 has been updated by nobu (Nobuyoshi Nakada). The interface of `fpconv_dtoa()` looks quite different from `dtoa()` in missing/dtoa.c. Rather `grisu2()` itself is closer? ---------------------------------------- Feature #21308: Replacing the Float#to_s (dtoa.c) implementation with a modern algorithm https://bugs.ruby-lang.org/issues/21308#change-112906 * Author: watson1978 (Shizuo Fujita) * Status: Open ---------------------------------------- This is a feature request to replace Ruby's `Float#to_s` implementation with a modern high-performance float-to-string conversion algorithm such as Grisu. Currently, `Float#to_s` in Ruby uses the BSD-derived implementation in [missing/dtoa.c](https://github.com/ruby/ruby/blob/master/missing/dtoa.c). Meanwhile, `json` gem has adopted a Grisu-based implementation in [ruby/json#768](https://github.com/ruby/json/pull/768), it has been improve the performance of float-to-string conversion dramatically. It appears to have brought about a 10 times improvement in performance. However, the improvement is limited to the `json` gem. If we can use the same implementation in `Float#to_s`, it will introduce the improvement in all float-to-string conversion cases. (In additional, it would be better if an API could be added that could be called directly from the C extension library, it will reduce the overhead of the call.) -- https://bugs.ruby-lang.org/