[JMT] Make sure smooth_abs is 0 at x=0

juanmanzanero · Aug 2, 2024 · ab0ba7d · ab0ba7d
1 parent 746b4a3
commit ab0ba7d
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Showing 2 changed files with 11 additions and 11 deletions.
diff --git a/lion/foundation/utils.h b/lion/foundation/utils.h
@@ -143,17 +143,17 @@ constexpr T smooth_neg_derivative(const T &x, S eps2);
 template<bool ActuallySmooth = true, typename T, typename S>
 constexpr T smooth_neg_second_derivative(const T &x, S eps2);
 
-template<bool ActuallySmooth = true, bool UseSinAtanFormula = true, typename T, typename S>
+template<bool ActuallySmooth = true, bool UseSmoothAbsFormula = true, typename T, typename S>
 constexpr T smooth_sign(const T &x, S eps);
 
-template<bool ActuallySmooth = true, bool UseSinAtanFormula = true, typename T, typename S>
+template<bool ActuallySmooth = true, bool UseSmoothAbsFormula = true, typename T, typename S>
 constexpr T smooth_sign_derivative(const T &x, S eps);
 
 template<bool ActuallySmooth = true, typename T, typename S>
-constexpr T smooth_abs(const T &x, S eps2);
+constexpr T smooth_abs(const T &x, S eps);
 
 template<bool ActuallySmooth = true, typename T, typename S>
-constexpr T smooth_hypot(const T &x, const T &y, S eps2);
+constexpr T smooth_hypot(const T &x, const T &y, S eps);
 
 template<bool ActuallySmooth = true, typename T, typename T1, typename S>
 constexpr T smooth_max(const T &x, const T1 &lo, S eps);

diff --git a/lion/foundation/utils.hpp b/lion/foundation/utils.hpp
@@ -315,7 +315,7 @@ constexpr T smooth_sign(const T &x, S eps)
 
     if constexpr (ActuallySmooth) {
         if constexpr (UseSmoothAbsFormula) {
-            return x / smooth_abs(x, eps * eps);
+            return x / sqrt(x * x + eps * eps);
         }
         else {
             using std::tanh;
@@ -370,7 +370,7 @@ constexpr T smooth_sign_derivative(const T &x, S eps)
 
 
 template<bool ActuallySmooth, typename T, typename S>
-constexpr T smooth_abs(const T &x, S eps2)
+constexpr T smooth_abs(const T &x, S eps)
 {
     //
     // Returns the absolute value of input "x", smoothed
@@ -383,20 +383,20 @@ constexpr T smooth_abs(const T &x, S eps2)
     if constexpr (ActuallySmooth) {
         using std::sqrt;
 
-        return sqrt(x * x + eps2);
+        return sqrt(x * x + eps * eps) - eps;
     }
     else {
         using std::abs;
 
-        (void)eps2;
+        (void)eps;
 
         return abs(x);
     }
 }
 
 
 template<bool ActuallySmooth, typename T, typename S>
-constexpr T smooth_hypot(const T &x, const T &y, S eps2)
+constexpr T smooth_hypot(const T &x, const T &y, S eps)
 {
     //
     // Returns "sqrt(x^2 + y^2)", smoothed out near [0, 0]
@@ -408,13 +408,13 @@ constexpr T smooth_hypot(const T &x, const T &y, S eps2)
     if constexpr (ActuallySmooth) {
         using std::sqrt;
 
-        return sqrt(x * x + y * y + eps2);
+        return sqrt(x * x + y * y + eps * eps) - eps;
     }
     else {
         //using std::hypot; -> not implemented in CppAD
         using std::sqrt;
 
-        (void)eps2;
+        (void)eps;
 
         //return hypot(x, y);
         return sqrt(x * x + y * y);