From 0521525e1f17a002fe807124d3a46ac648607aa2 Mon Sep 17 00:00:00 2001
From: leo <wanderer@dotya.ml>
Date: Tue, 7 Feb 2023 23:33:00 +0100
Subject: [PATCH] cec2020: implement Hybrid1 func

---
 bench/cec2020/benchFunctions.go  | 35 +++++++++++++++++++++++++++++++-
 bench/cec2020/helperFunctions.go | 24 ++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/bench/cec2020/benchFunctions.go b/bench/cec2020/benchFunctions.go
index ecc6d41..01b951e 100644
--- a/bench/cec2020/benchFunctions.go
+++ b/bench/cec2020/benchFunctions.go
@@ -103,7 +103,40 @@ func RosenbrockGriewank(x []float64) float64 {
 }
 
 // Hybrid1 is the "Hybrid Function 1" of CEC2020.
-func Hybrid1(x []float64) float64 { return 0 }
+func Hybrid1(x []float64) float64 {
+	nx := len(x)
+	fnx := float64(nx)
+
+	f1 := SchwefelModified
+	f2 := Rastrigin
+	f3 := HighConditionedElliptic
+
+	// percentages.
+	p := []float64{0.3, 0.3, 0.4}
+	gnx := make([]float64, len(p))
+	gnxsum := 0.0
+
+	for i := 0; i < len(p)-1; i++ {
+		gnx[i] = math.Ceil(p[i] * fnx)
+		gnxsum += gnx[i]
+	}
+
+	gnx[len(p)] = fnx - gnxsum
+
+	z := newOpt(nx)
+	mz := make([]float64, nx)
+
+	for i := range x {
+		mz = append(mz, x[i]*z[i])
+	}
+
+	// results.
+	r1 := f1(mz)
+	r2 := f2(mz)
+	r3 := f3(mz)
+
+	return gnx[0]*r1 + gnx[1]*r2 + gnx[2]*r3
+}
 
 // Hybrid2 is the "Hybrid Function 2" of CEC2020.
 func Hybrid2(x []float64) float64 { return 0 }
diff --git a/bench/cec2020/helperFunctions.go b/bench/cec2020/helperFunctions.go
index 80a1889..883ec8c 100644
--- a/bench/cec2020/helperFunctions.go
+++ b/bench/cec2020/helperFunctions.go
@@ -140,3 +140,27 @@ func newXopt(n int, mu0 float64) []float64 {
 
 	return xopt
 }
+
+// newOpt returns a slice of optimal float64 values.
+func newOpt(n int) []float64 {
+	uniformDist := &distuv.Uniform{
+		Src: rand.NewSource(uint64(time.Now().UnixNano())),
+		Min: SearchRange.Min(),
+		Max: SearchRange.Max(),
+	}
+
+	tmpvec := make([]float64, n)
+	xopt := make([]float64, n)
+
+	for i := 0; i < n; i++ {
+		tmpvec = append(tmpvec, uniformDist.Rand())
+
+		xopt = append(xopt, 0.5*uniformDist.Mean())
+
+		if tmpvec[i] < 0 {
+			xopt[i] *= -1
+		}
+	}
+
+	return xopt
+}