diff --git a/bench/cec2020/basicFunctions.go b/bench/cec2020/basicFunctions.go
index 96bbae9..98682bd 100644
--- a/bench/cec2020/basicFunctions.go
+++ b/bench/cec2020/basicFunctions.go
@@ -16,7 +16,16 @@ func HighConditionedElliptic(x []float64) float64 { return 0 }
 func HGBat(x []float64) float64 { return 0 }
 
 // Rosenbrock is the "Rosenbrock's Function" of CEC2020.
-func Rosenbrock(x []float64) float64 { return 0 }
+// ref: https://infinity77.net/global_optimization/test_functions_nd_R.html#go_benchmark.Rosenbrock
+func Rosenbrock(x []float64) float64 {
+	var sum float64
+
+	for i := 0; i < len(x)-1; i++ {
+		sum += 100*(math.Pow(math.Pow(x[i], 2)-x[i+1], 2)) + math.Pow(x[i]-1, 2)
+	}
+
+	return sum
+}
 
 // Griewank is the "Griewank's Function" of CEC2020.
 // ref: https://www.sfu.ca/~ssurjano/griewank.html