Replace division of exponential in Gamma loss (#4289)

32fec820 · Christian Lorentzen · GitHub · 08c38efc · 32fec820
Unverified Commit 32fec820 authored May 18, 2021 by Christian Lorentzen Committed by GitHub May 18, 2021
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src/objective/regression_objective.hpp src/objective/regression_objective.hpp +4 -4

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--- a/src/objective/regression_objective.hpp
+++ b/src/objective/regression_objective.hpp
@@ -689,14 +689,14 @@ class RegressionGammaLoss : public RegressionPoissonLoss {
    if (weights_ == nullptr) {
      #pragma omp parallel for schedule(static)
      for (data_size_t i = 0; i < num_data_; ++i) {
-        gradients[i] = static_cast<score_t>(1.0 - label_[i] / std::exp(score[i]));
-        hessians[i] = static_cast<score_t>(label_[i] / std::exp(score[i]));
+        gradients[i] = static_cast<score_t>(1.0 - label_[i] * std::exp(-score[i]));
+        hessians[i] = static_cast<score_t>(label_[i] * std::exp(-score[i]));
      }
    } else {
      #pragma omp parallel for schedule(static)
      for (data_size_t i = 0; i < num_data_; ++i) {
-        gradients[i] = static_cast<score_t>(1.0 - label_[i] / std::exp(score[i]) * weights_[i]);
-        hessians[i] = static_cast<score_t>(label_[i] / std::exp(score[i]) * weights_[i]);
+        gradients[i] = static_cast<score_t>(1.0 - label_[i] * std::exp(-score[i]) * weights_[i]);
+        hessians[i] = static_cast<score_t>(label_[i] * std::exp(-score[i]) * weights_[i]);
      }
    }
  }