// Copyright 2022 wanderer <a_mirre at utb dot cz>
// SPDX-License-Identifier: GPL-3.0-or-later

package bench

import "math"

// Functions is a string-func map of function names and specific bench funcs
// for easier iterable access.
var Functions = map[string]func([]float64) float64{
	"Schwefel":    Schwefel,
	"De Jong 1st": DeJong1st,
	"De Jong 2nd": DeJong2nd,
}

var FuncNames = map[int]string{
	0: "Schwefel",
	1: "De Jong 1st",
	2: "De Jong 2nd",
}

// Function params maps function names to their funcParams for easier iterable
// access.
var FunctionParams = map[string]funcParams{
	"Schwefel":    SchwefelParams,
	"De Jong 1st": DeJong1Params,
	"De Jong 2nd": DeJong2Params,
}

// Schwefel computes the value of the Schwefel function for x.
func Schwefel(x []float64) float64 {
	var res float64

	for _, val := range x {
		res += val * math.Sin(math.Sqrt(math.Abs(val)))
	}

	return 418.9829*float64(len(x)) - res
}

// DeJong1st computes the value of the 1st De Jong function for x.
func DeJong1st(x []float64) float64 {
	var res float64

	for _, val := range x {
		res += math.Pow(val, 2)
	}

	return res
}

// DeJong2nd computes the value of the 2nd De Jong function for x.
func DeJong2nd(x []float64) float64 {
	var res float64

	for _, val := range x {
		res += math.Floor(val)
	}

	return res
}