chore: begin impementing sine function using Taylor series expansion

BastianAsmussen · Jan 9, 2025 · c0fa295 · c0fa295
1 parent fd7ba76
commit c0fa295
Showing 1 changed file with 21 additions and 0 deletions.
diff --git a/lib/math.nix b/lib/math.nix
@@ -3,6 +3,27 @@ _: rec {
 
   PI = 3.14159265358979323846;
 
+  sin = let
+    s1 = 1.0 / fact 3.0;
+    s2 = 1.0 / fact 5.0;
+    s3 = 1.0 / fact 7.0;
+    s4 = 1.0 / fact 9.0;
+    s5 = 1.0 / fact 11.0;
+
+    polynomial' = xx: (((s5 * xx + s4) * xx + s3) * xx + s2) * xx;
+    polynomial = xx: (polynomial' xx) + s1;
+
+    t = xx: x: dx: ((polynomial xx) * x - 0.5 * dx) * xx + dx;
+    taylorSin = xx: x: dx: let
+      dx' =
+        if x <= 0.0
+        then -dx
+        else dx;
+    in
+      x + (t xx x dx');
+  in
+    x: taylorSin (x * x) x 0.0;
+
   mod = a: n: let
     quotient = div a n;
   in