From 62ce28852429a5a0ef74c4cf270f2da0738cfd84 Mon Sep 17 00:00:00 2001
From: emma <emma@tebibyte.media>
Date: Wed, 4 Sep 2024 22:12:44 -0600
Subject: [PATCH] rpn(1): makes rounding more efficient

---
 src/rpn.rs | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/rpn.rs b/src/rpn.rs
index 6907772..7383201 100644
--- a/src/rpn.rs
+++ b/src/rpn.rs
@@ -129,10 +129,6 @@ impl StrError for EvaluationError {
 	}
 }
 
-/* I’m no math nerd but I want the highest possible approximation of 0.9
- * repeating and it seems this can give it to me */
-const PRECISION_MOD: f64 = 0.9 + f64::EPSILON;
-
 fn err<T: StrError>(argv0: &String, e: &T, code: Option<u8>) -> ExitCode {
 	eprintln!("{}: {}", argv0, e.strerror());
 	ExitCode::from(code.unwrap_or(1 /* unknown error */))
@@ -211,9 +207,9 @@ fn eval(
 fn round_precise(value: &f64) -> f64 {
 	/* Set floating-point precision for correcting rounding errors based on
 	 * machine epsilon */
-	let precision = (-f64::EPSILON.log10() * PRECISION_MOD).ceil() as i32;
-	
-	let multiplier = 10_f64.powi(precision as i32);
+	let precision = (-f64::EPSILON.log10()).floor() as i32;
+	let multiplier = 10_f64.powi(precision);
+
 	(value * multiplier).round() / multiplier
 }