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7 commits

Author SHA1 Message Date
Leo
bb599667c0
Merge aa070c4ec8 into 80ec940054 2024-04-12 16:03:12 +08:00
Egor Seredin
80ec940054
Add NewFromUint64 constructor (#352) 2024-04-08 16:38:20 +02:00
Mateusz Woś
2fa107d0fe
Remove production usage from docs (#362) 2024-04-07 20:33:44 +02:00
Philip Dubé
645a76e5b0
Optimize BigInt (#359) 2024-04-05 21:43:23 +02:00
Mateusz Woś
ed8f76e893
Drop support for Go versions older than 1.10 (#361)
* Drop support for Go versions older than 1.10
* Remove 1.18 from test suite
2024-04-05 21:41:05 +02:00
Leonardo
aa070c4ec8 make Sqrt a method of Decimal; add unit tests (1 failing) 2021-03-27 13:52:30 -07:00
Leonardo Cicconi
a68916bc93 added Sqrt and SqrtRound functions 2021-03-25 17:42:49 -07:00
5 changed files with 136 additions and 19 deletions

View file

@ -9,7 +9,7 @@ jobs:
runs-on: ubuntu-latest
strategy:
matrix:
go: [ '1.7.x', '1.18', '1.19', '1.20', '1.21', '1.x' ]
go: [ '1.10.x', '1.19', '1.20', '1.21', '1.22', '1.x' ]
name: Go ${{ matrix.go }}
steps:
- uses: actions/checkout@v4

View file

@ -22,7 +22,7 @@ Run `go get github.com/shopspring/decimal`
## Requirements
Decimal library requires Go version `>=1.7`
Decimal library requires Go version `>=1.10`
## Usage
@ -63,11 +63,6 @@ func main() {
http://godoc.org/github.com/shopspring/decimal
## Production Usage
* [Spring](https://shopspring.com/), since August 14, 2014.
* If you are using this in production, please let us know!
## FAQ
#### Why don't you just use float64?

View file

@ -19,6 +19,7 @@ package decimal
import (
"database/sql/driver"
"encoding/binary"
"errors"
"fmt"
"math"
"math/big"
@ -130,6 +131,18 @@ func NewFromInt32(value int32) Decimal {
}
}
// NewFromUint64 converts an uint64 to Decimal.
//
// Example:
//
// NewFromUint64(123).String() // output: "123"
func NewFromUint64(value uint64) Decimal {
return Decimal{
value: new(big.Int).SetUint64(value),
exp: 0,
}
}
// NewFromBigInt returns a new Decimal from a big.Int, value * 10 ^ exp
func NewFromBigInt(value *big.Int, exp int32) Decimal {
return Decimal{
@ -1406,9 +1419,7 @@ func (d Decimal) IntPart() int64 {
// BigInt returns integer component of the decimal as a BigInt.
func (d Decimal) BigInt() *big.Int {
scaledD := d.rescale(0)
i := &big.Int{}
i.SetString(scaledD.String(), 10)
return i
return scaledD.value
}
// BigFloat returns decimal as BigFloat.
@ -2322,3 +2333,59 @@ func (d Decimal) Tan() Decimal {
}
return y
}
// More math
// Sqrt returns the square root of d, accurate to DivisionPrecision decimal places.
// Sqrt is only valid for non-negative numbers; it will return an error otherwise.
func (d Decimal) Sqrt() (Decimal, error) {
s, _, err := d.SqrtRound(int32(DivisionPrecision))
return s, err
}
// ErrImaginaryResult indicates an operation that would produce an imaginary result.
var ErrImaginaryResult = errors.New("The result of this operation is imaginary.")
// SqrtMaxIter sets a limit for number of iterations for the Sqrt function
const SqrtMaxIter = 1000000
// SqrtRound returns the square root of d, accurate to precision decimal places.
// The bool precise returns whether the precision was achieved.
// SqrtRound is only valid for non-negative numbers; it will return an error otherwise.
func (d Decimal) SqrtRound(precision int32) (Decimal, bool, error) {
var (
maxError = New(1, -precision)
one = NewFromFloat(1)
lo, hi Decimal
)
// Handle cases where d < 0, d = 0, 0 < d < 1, and d > 1
if d.GreaterThanOrEqual(one) {
lo = Zero
hi = d
} else if d.Equal(one) {
return one, true, nil
} else if d.LessThan(Zero) {
return Zero, false, ErrImaginaryResult
} else if d.Equal(Zero) {
return Zero, true, nil
} else {
// d is between 0 and 1. Therefore, 0 < d < Sqrt(d) < 1.
lo = d
hi = one
}
var mid Decimal
for i := 0; i < SqrtMaxIter; i++ {
mid = lo.Add(hi).Div(New(2, 0)) //mid = (lo+hi)/2;
if mid.Mul(mid).Sub(d).Abs().LessThan(maxError) {
return mid, true, nil
}
if mid.Mul(mid).GreaterThan(d) {
hi = mid
} else {
lo = mid
}
}
return mid, false, nil
}

View file

@ -480,6 +480,7 @@ func TestNewFromInt(t *testing.T) {
1: "1",
323412345: "323412345",
9223372036854775807: "9223372036854775807",
-9223372036854775808: "-9223372036854775808",
}
// add negatives
@ -505,6 +506,7 @@ func TestNewFromInt32(t *testing.T) {
1: "1",
323412345: "323412345",
2147483647: "2147483647",
-2147483648: "-2147483648",
}
// add negatives
@ -524,6 +526,25 @@ func TestNewFromInt32(t *testing.T) {
}
}
func TestNewFromUint64(t *testing.T) {
tests := map[uint64]string{
0: "0",
1: "1",
323412345: "323412345",
9223372036854775807: "9223372036854775807",
18446744073709551615: "18446744073709551615",
}
for input, s := range tests {
d := NewFromUint64(input)
if d.String() != s {
t.Errorf("expected %s, got %s (%s, %d)",
s, d.String(),
d.value.String(), d.exp)
}
}
}
func TestNewFromBigIntWithExponent(t *testing.T) {
type Inp struct {
val *big.Int
@ -3460,6 +3481,40 @@ func TestAvg(t *testing.T) {
}
}
func TestSqrtRound(t *testing.T) {
i := NewFromFloat(-1)
if _, err := i.Sqrt(); err != ErrImaginaryResult {
t.Errorf("Square root of -1 should produce error")
}
var vals = map[string]string{
// value : Sqrt(value)
"0.0": "0.0",
"0.002342": "0.0483942145302514",
"1.0": "1.0",
"3.0": "1.7320508075688773",
"4.0": "2.0",
"4.5": "2.1213203435596426",
"3289854.0": "1813.7954680724064485",
}
for val, expected := range vals {
v, err := NewFromString(val)
if err != nil {
t.Errorf("error parsing test value into Decimal")
}
e, err := NewFromString(expected)
if err != nil {
t.Errorf("error parsing test expected value into Decimal")
}
if sqrt, err := v.Sqrt(); err != nil || !sqrt.Equal(e) {
t.Errorf("Square root of %s should be %s, not %s (error: %s)", v, e, sqrt, err)
}
}
}
func TestRoundBankAnomaly(t *testing.T) {
a := New(25, -1)
b := New(250, -2)

2
go.mod
View file

@ -1,3 +1,3 @@
module github.com/shopspring/decimal
go 1.7
go 1.10