cec2020: implement LunacekBiRastrigin func

bench/cec2020/benchFunctions.go

@@ -48,7 +48,42 @@ func Schwefel(x []float64) float64 {
 }
 
 // LunacekBiRastrigin is the "Shifted and Rotated Lunacek bi-Rastrigin Function" of CEC2020.
-func LunacekBiRastrigin(x []float64) float64 { return 0 }
+func LunacekBiRastrigin(x []float64) float64 {
+	var sum0 float64
+
+	var sum1 float64
+
+	var sum2 float64
+
+	nx := len(x)
+	fnx := float64(nx)
+	s := 1 - (1 / ((2 * math.Sqrt(fnx+20)) - 8.2))
+	d := 1.0
+	mu0 := 2.5
+	mu1 := -math.Sqrt((math.Pow(mu0, 2) - d) / s)
+	xhat := make([]float64, nx)
+	xopt := newXopt(nx, mu0)
+
+	for i := range x {
+		xhat = append(xhat, 2*x[i])
+
+		if xopt[i] < 0 {
+			xhat[i] *= -1
+		}
+	}
+
+	for i := range x {
+		sum0 += math.Pow(xhat[i]-mu0, 2)
+
+		sum1 += math.Pow(xhat[i]-mu1, 2)
+
+		zi := math.Pow(100, 0.5*((float64(i)-1)/fnx-1)) * xhat[i]
+
+		sum2 += (1 - math.Cos(2*math.Pi*zi))
+	}
+
+	return math.Min(sum0, (d*fnx)+(s*sum1)) + 10*sum2
+}
 
 // RosenbrockGriewank is the "Expanded Rosenbrock's plus Griewank's Function"
 // of CEC2020.

bench/cec2020/constants.go

@@ -9,3 +9,8 @@ package cec2020
 #define E  2.7182818284590452353602874713526625
 #define PI 3.1415926535897932384626433832795029
 */
+
+const (
+	searchRangeMin = -100
+	searchRangeMax = 100
+)

bench/cec2020/helperFunctions.go

@@ -3,7 +3,14 @@
 
 package cec2020
 
-import "math"
+import (
+	"math"
+	"time"
+
+	"golang.org/x/exp/rand"
+
+	"gonum.org/v1/gonum/stat/distuv"
+)
 
 // void hf01 (double *, double *, int, double *,double *, int *,int, int); // Hybrid Function 1
 // void hf02 (double *, double *, int, double *,double *, int *,int, int); // Hybrid Function 2
@@ -112,3 +119,26 @@ func Asy(x []float64, beta float64) {
 		}
 	}
 }
+
+func newXopt(n int, mu0 float64) []float64 {
+	gaussDist := &distuv.Uniform{
+		Src: rand.NewSource(uint64(time.Now().UnixNano())),
+		Min: searchRangeMin,
+		Max: searchRangeMax,
+	}
+
+	tmpvec := make([]float64, n)
+	xopt := make([]float64, n)
+
+	for i := 0; i < n; i++ {
+		tmpvec = append(tmpvec, gaussDist.Rand())
+
+		xopt = append(xopt, 0.5*mu0)
+
+		if tmpvec[i] < 0 {
+			xopt[i] *= -1
+		}
+	}
+
+	return xopt
+}

bench/cec2020/vars.go

@@ -3,7 +3,14 @@
 
 package cec2020
 
+import "git.dotya.ml/wanderer/math-optim/bench"
+
 /*
 extern double *OShift,*M,*y,*z,*x_bound;
 extern int ini_flag,n_flag,func_flag,*SS;
 */
+
+var Functions = map[string]func([]float64) float64{}
+
+// SearchRange specifies the CEC2020 search range.
+var SearchRange = bench.NewfuncParams(searchRangeMin, searchRangeMax)