Fix Adam optimizer unit test

unit_tests/optimizer/Test_Adam.cpp

@@ -119,9 +119,9 @@ TEST_CASE("[learning/Adam] update", "[Optimizer][Adam]") {
             REQUIRE(approxEq<float,float>(tmpt2, tmpt1, 1e-5f, 1e-8f));
         }
 
-        // truth
         for (std::size_t step = 0; step < 10; ++step) {
-            float lr2 = lr * std::sqrt(1.0f - std::pow(beta1, step + 1)) / (1.0f - std::pow(beta1, step + 1));
+            // truth
+            float lr2 = lr * std::sqrt(1.0f - std::pow(beta2, step + 1)) / (1.0f - std::pow(beta1, step + 1));
             float epsilon2 = epsilon * std::sqrt(1.0f - std::pow(beta2, step + 1));
             for (std::size_t t = 0; t < nb_tensors; ++t) {
                 for (std::size_t i = 0; i < size_tensors[t]; ++i) {