// Copyright © 2016 Abcum Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package math

import "math"

func Spread(vals []float64) float64 {

	var min, max float64

	switch len(vals) {
	case 0:
		return math.NaN()
	case 1:
		return 0
	}

	for _, v := range vals {
		switch {
		case v < min:
			min = v
		case v > max:
			max = v
		}
	}

	return (max - min) - 1

}