Function format_real_precise 

pub fn format_real_precise(value: f64) -> String

Formats a real number with 15 significant digits (igraph_real_snprintf_precise), as used by igraph’s writers.

use igraph::vector::format_real_precise;
assert_eq!(format_real_precise(0.1), "0.1");
assert_eq!(format_real_precise(1.0 / 3.0), "0.333333333333333");