f use const

lightning/src/routing/scoring.rs

@@ -727,10 +727,10 @@ impl<L: Deref<Target = u64>, T: Time, U: Deref<Target = T>> DirectedChannelLiqui
 		} else {
 			let numerator = (max_liquidity_msat - amount_msat).saturating_add(1);
 			let denominator = (max_liquidity_msat - min_liquidity_msat).saturating_add(1);
-			if amount_msat - min_liquidity_msat < denominator / 64 {
-				// If the failure probability is < 1.5625%, don't bother trying to use the log
-				// approximation as it gets too noisy to be particularly helpful, instead just
-				// round down to 0 and return the base penalty.
+			if amount_msat - min_liquidity_msat < denominator / approx::PRECISION_LOWER_BOUND_DENOMINATOR {
+				// If the failure probability is < 1.5625% (in the form of 1 - numerator/denominator < 1/64),
+				// don't bother trying to use the log approximation as it gets too noisy to be particularly
+				// helpful, instead just round down to 0 and return the base penalty.
 				params.base_penalty_msat
 			} else {
 				let negative_log10_times_2048 =
@@ -898,6 +898,9 @@ mod approx {
 	const LOWER_BITS: u32 = 6;
 	const LOWER_BITS_BOUND: u64 = 1 << LOWER_BITS;
 	const LOWER_BITMASK: u64 = (1 << LOWER_BITS) - 1;
+	/// The rough cutoff at which our precision falls off and we should stop bothering to try to
+	/// log a ratio, as X in 1/X.
+	pub(super) const PRECISION_LOWER_BOUND_DENOMINATOR: u64 = LOWER_BITS_BOUND;
 
 	/// Look-up table for `log10(x) * 2048` where row `i` is used for each `x` having `i` as the
 	/// most significant bit. The next 4 bits of `x`, if applicable, are used for the second index.