Merge pull request #382 from LouiseMsn/log-barrier-fix

Fix for LogResidualCost

Author: ManifoldFR

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed the missing minus signs in the `LogResidualCost` (https://github.com/Simple-Robotics/aligator/pull/382)
+
 ## [0.17.1] - 2025-12-01
 
 ## [0.17.0] - 2025-11-21

include/aligator/modelling/costs/log-residual-cost.hpp

@@ -5,8 +5,20 @@
 #include "./composite-costs.hpp"
 
 namespace aligator {
-
-/// @brief  Log-barrier of an underlying cost function.
+/**
+ * @brief  Log-barrier of an underlying cost function.
+ *
+ * @details Defined as :
+ * \f[
+ *      c(x,u) = -w\ln(r(x,u))
+ * \f]
+ *
+ * where :
+ *    -\f(\ c(x,u) \f) is the resulting cost
+ *    -\f(\ r(x,u) \f) is the input function
+ *    -\f(\ w \f) is the input scale
+ *
+ */
 template <typename Scalar> struct LogResidualCostTpl : CostAbstractTpl<Scalar> {
   ALIGATOR_DYNAMIC_TYPEDEFS(Scalar);
   using CostDataAbstract = CostDataAbstractTpl<Scalar>;

include/aligator/modelling/costs/log-residual-cost.hxx

@@ -38,7 +38,7 @@ void LogResidualCostTpl<Scalar>::evaluate(const ConstVectorRef &x,
   Data &d = static_cast<Data &>(data);
   residual_->evaluate(x, u, *d.residual_data);
   d.value_ =
-      barrier_weights_.dot(d.residual_data->value_.array().log().matrix());
+      -barrier_weights_.dot(d.residual_data->value_.array().log().matrix());
 }
 
 template <typename Scalar>
@@ -54,7 +54,7 @@ void LogResidualCostTpl<Scalar>::computeGradients(
   const int nrows = residual_->nr;
   for (int i = 0; i < nrows; i++) {
     auto g_i = J.row(i);
-    d.grad_.noalias() += barrier_weights_(i) * g_i / v(i);
+    d.grad_.noalias() += -barrier_weights_(i) * g_i / v(i);
   }
 }
 
@@ -72,7 +72,7 @@ void LogResidualCostTpl<Scalar>::computeHessians(const ConstVectorRef &,
   for (int i = 0; i < nrows; i++) {
     auto g_i = J.row(i); // row vector
     d.hess_.noalias() +=
-        barrier_weights_(i) * (g_i.transpose() * g_i) / (v(i) * v(i));
+        -barrier_weights_(i) * (g_i.transpose() * g_i) / (v(i) * v(i));
   }
 }
 } // namespace aligator