From 25fca052f5b55c8d3fc4aef1e71dc7d0ab751cdd Mon Sep 17 00:00:00 2001
From: Zachary Levy <zachary@sunforge.is>
Date: Sun, 29 Mar 2026 20:29:24 -0700
Subject: [PATCH] Switch from custom LN_2 constant to math.LN2

---
 .zed/tasks.json      | 5 +++++
 levmath/levmath.odin | 9 ++++-----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/.zed/tasks.json b/.zed/tasks.json
index 63f392a..d49b77d 100644
--- a/.zed/tasks.json
+++ b/.zed/tasks.json
@@ -22,6 +22,11 @@
     "command": "odin test levsync -out=out/debug/test_levsync",
     "cwd": "$ZED_WORKTREE_ROOT"
   },
+  {
+    "label": "Test levmath",
+    "command": "odin test levmath -out=out/debug/test_levmath",
+    "cwd": "$ZED_WORKTREE_ROOT"
+  },
   // ---------------------------------------------------------------------------------------------------------------------
   // ----- LMDB Examples ------------------------
   // ---------------------------------------------------------------------------------------------------------------------
diff --git a/levmath/levmath.odin b/levmath/levmath.odin
index cbd6de3..b9ddaa6 100644
--- a/levmath/levmath.odin
+++ b/levmath/levmath.odin
@@ -34,14 +34,13 @@ import "core:testing"
 //   Neural Computation 11, 853–862 (1999).
 //   J. Rade, FastExp.h (2021), https://gist.github.com/jrade/293a73f89dfef51da6522428c857802d
 fast_exp :: #force_inline proc "contextless" (x: $FLOAT) -> FLOAT where intrinsics.type_is_float(FLOAT) {
-	LN_2 :: 0.6931471805599453
 	CORRECTION :: 0.04367744890362246
 
 	when FLOAT == f16 {
 		MANTISSA_BITS :: 10
 		EXPONENT_BIAS :: 15
 		SHIFT :: f16(1 << MANTISSA_BITS)
-		SCALE :: SHIFT / LN_2
+		SCALE :: SHIFT / math.LN2
 		BIAS  :: SHIFT * f16(EXPONENT_BIAS - CORRECTION)
 		MAX_Y :: SHIFT * (2 * EXPONENT_BIAS + 1)
 
@@ -52,7 +51,7 @@ fast_exp :: #force_inline proc "contextless" (x: $FLOAT) -> FLOAT where intrinsi
 		MANTISSA_BITS :: 23
 		EXPONENT_BIAS :: 127
 		SHIFT :: f32(1 << MANTISSA_BITS)
-		SCALE :: SHIFT / LN_2
+		SCALE :: SHIFT / math.LN2
 		BIAS  :: SHIFT * f32(EXPONENT_BIAS - CORRECTION)
 		MAX_Y :: SHIFT * (2 * EXPONENT_BIAS + 1)
 
@@ -63,7 +62,7 @@ fast_exp :: #force_inline proc "contextless" (x: $FLOAT) -> FLOAT where intrinsi
 		MANTISSA_BITS :: 52
 		EXPONENT_BIAS :: 1023
 		SHIFT :: f64(1 << MANTISSA_BITS)
-		SCALE :: SHIFT / LN_2
+		SCALE :: SHIFT / math.LN2
 		BIAS  :: SHIFT * f64(EXPONENT_BIAS - CORRECTION)
 		MAX_Y :: SHIFT * (2 * EXPONENT_BIAS + 1)
 
@@ -174,4 +173,4 @@ test_fast_exp_saturation :: proc(t: ^testing.T) {
 	ov64 := fast_exp(f64(1e5))
 	testing.expectf(t, math.is_inf_f32(ov32), "f32 overflow: got %v, want +inf", ov32)
 	testing.expectf(t, math.is_inf_f64(ov64), "f64 overflow: got %v, want +inf", ov64)
-}
\ No newline at end of file
+}