That “weirdness” is just scientific notation, which the Ryu implementation always emits. It is “superficial” in the sense that it’s separate from the core algor

That “weirdness” is just scientific notation, which the Ryu implementation always emits. It is “superficial” in the sense that it’s separate from the core algorithm. When I adapted it for C++17 charconv in MSVC, I implemented fixed, general, and “plain shortest” notation, which will print 0.3 there. (General notation follows C printf %g’s rules for switching between fixed and scientific; “plain shortest” notation selects the one that’s fewer characters, tiebreaking to prefer fixed).