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decimal.go
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decimal.go
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// Copyright (C) 2023 Gobalsky Labs Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package num
import (
"errors"
"math/big"
"github.com/shopspring/decimal"
)
type Decimal = decimal.Decimal
var (
dzero = decimal.Zero
d1 = decimal.NewFromFloat(1)
dm1 = decimal.NewFromFloat(-1)
d2 = decimal.NewFromFloat(2)
maxDecimal = decimal.NewFromBigInt(maxU256, 0)
e = MustDecimalFromString("2.7182818285")
)
func MustDecimalFromString(f string) Decimal {
d, err := DecimalFromString(f)
if err != nil {
panic(err)
}
return d
}
func DecimalOne() Decimal {
return d1
}
func DecimalMinusOne() Decimal {
return dm1
}
func DecimalTwo() Decimal {
return d2
}
func DecimalZero() Decimal {
return dzero
}
func DecimalE() Decimal {
return e
}
func MaxDecimal() Decimal {
return maxDecimal
}
func NewDecimalFromFloat(f float64) Decimal {
return decimal.NewFromFloat(f)
}
func NewDecimalFromBigInt(value *big.Int, exp int32) Decimal {
return decimal.NewFromBigInt(value, exp)
}
func DecimalFromUint(u *Uint) Decimal {
return decimal.NewFromUint(&u.u)
}
func DecimalFromInt(u *Int) Decimal {
d := decimal.NewFromUint(&u.U.u)
if u.IsNegative() {
return d.Neg()
}
return d
}
func DecimalFromInt64(i int64) Decimal {
return decimal.NewFromInt(i)
}
func DecimalFromFloat(v float64) Decimal {
return decimal.NewFromFloat(v)
}
func DecimalFromString(s string) (Decimal, error) {
return decimal.NewFromString(s)
}
func DecimalPart(a Decimal) Decimal {
return a.Sub(a.Floor())
}
func MaxD(a, b Decimal) Decimal {
if a.GreaterThan(b) {
return a
}
return b
}
func MinD(a, b Decimal) Decimal {
if a.LessThan(b) {
return a
}
return b
}
// calculates the mean of a given slice.
func Mean(numbers []Decimal) (Decimal, error) {
if len(numbers) == 0 {
return DecimalZero(), errors.New("cannot calculate the mean of an empty list")
}
total := DecimalZero()
for _, num := range numbers {
total = total.Add(num)
}
return total.Div(DecimalFromInt64(int64(len(numbers)))), nil
}
// calculates the variance of a decimal slice.
func Variance(numbers []Decimal) (Decimal, error) {
if len(numbers) == 0 {
return DecimalZero(), errors.New("cannot calculate the variance of an empty list")
}
m, _ := Mean(numbers)
total := DecimalZero()
for _, num := range numbers {
total = total.Add(num.Sub(m).Pow(d2))
}
return total.Div(DecimalFromInt64(int64(len(numbers)))), nil
}
func UnmarshalBinaryDecimal(data []byte) (Decimal, error) {
d := decimal.New(0, 1)
err := d.UnmarshalBinary(data)
return d, err
}