add abs function

neilkichler · Jul 8, 2024 · 2bbc6e8 · 2bbc6e8
1 parent 95d19f8
commit 2bbc6e8
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/include/cutangent/arithmetic/basic.cuh b/include/cutangent/arithmetic/basic.cuh
@@ -59,6 +59,15 @@ fn tangent<T> min(tangent<T> a, tangent<T> b)
              .d = a.v <= b.v ? a.d : b.d }; // '<=' instead of '<' due to subgradient
 }
 
+template<typename T>
+fn tangent<T> abs(tangent<T> x)
+{
+    using std::abs;
+    using std::copysign;
+    // NOTE: not differentiable at x = 0.
+    return { .v = abs(x.v), .d = copysign(1.0, x.v) * x.d };
+}
+
 template<typename T>
 fn tangent<T> clamp(tangent<T> v, tangent<T> lb, tangent<T> ub)
 {