decimal

package
v1.7.5 Latest Latest
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 Go to latest Published: Dec 26, 2023 License: Apache-2.0 Imports: 8 Imported by: 1

Documentation

Overview

Package decimal implements an arbitrary precision fixed-point decimal.

The zero-value of a Decimal is 0, as you would expect.

The best way to create a new Decimal is to use decimal.NewFromString, ex: 

n, err := decimal.NewFromString("-123.4567")
n.String() // output: "-123.4567"

To use Decimal as part of a struct: 

type Struct struct {
    Number Decimal
}

Note: This can "only" represent numbers with a maximum of 2^31 digits after the decimal point.

Index

Constants

This section is empty.

Variables

View Source 
var DivisionPrecision = 16

DivisionPrecision is the number of decimal places in the result when it doesn't divide exactly.

Example: 

d1 := decimal.NewFromFloat(2).Div(decimal.NewFromFloat(3))
d1.String() // output: "0.6666666666666667"
d2 := decimal.NewFromFloat(2).Div(decimal.NewFromFloat(30000))
d2.String() // output: "0.0000666666666667"
d3 := decimal.NewFromFloat(20000).Div(decimal.NewFromFloat(3))
d3.String() // output: "6666.6666666666666667"
decimal.DivisionPrecision = 3
d4 := decimal.NewFromFloat(2).Div(decimal.NewFromFloat(3))
d4.String() // output: "0.667"
View Source 
var ExpMaxIterations = 1000

ExpMaxIterations specifies the maximum number of iterations needed to calculate precise natural exponent value using ExpHullAbrham method.

View Source 
var MarshalJSONWithoutQuotes = false

MarshalJSONWithoutQuotes should be set to true if you want the decimal to be JSON marshaled as a number, instead of as a string. WARNING: this is dangerous for decimals with many digits, since many JSON unmarshallers (ex: Javascript's) will unmarshal JSON numbers to IEEE 754 double-precision floating point numbers, which means you can potentially silently lose precision.

View Source 
var Zero = New(0, 1)

Zero constant, to make computations faster. Zero should never be compared with == or != directly, please use decimal.Equal or decimal.Cmp instead.

Functions

func RescalePair 

func RescalePair(d1 Decimal, d2 Decimal) (Decimal, Decimal)

RescalePair rescales two decimals to common exponential value (minimal exp of both decimals)

Types

type Decimal 

type Decimal struct {
	// contains filtered or unexported fields
}

Decimal represents a fixed-point decimal. It is immutable. number = value * 10 ^ exp

func Avg 

func Avg(first Decimal, rest ...Decimal) Decimal

Avg returns the average value of the provided first and rest Decimals

func Max 

func Max(first Decimal, rest ...Decimal) Decimal

Max returns the largest Decimal that was passed in the arguments.

To call this function with an array, you must do: 

Max(arr[0], arr[1:]...)

This makes it harder to accidentally call Max with 0 arguments.

func Min 

func Min(first Decimal, rest ...Decimal) Decimal

Min returns the smallest Decimal that was passed in the arguments.

To call this function with an array, you must do: 

Min(arr[0], arr[1:]...)

This makes it harder to accidentally call Min with 0 arguments.

func New 

func New(value int64, exp int32) Decimal

New returns a new fixed-point decimal, value * 10 ^ exp.

func NewFromBigInt 

func NewFromBigInt(value *big.Int, exp int32) Decimal

NewFromBigInt returns a new Decimal from a big.Int, value * 10 ^ exp

func NewFromFloat 

func NewFromFloat(value float64) Decimal

NewFromFloat converts a float64 to Decimal.

The converted number will contain the number of significant digits that can be represented in a float with reliable roundtrip. This is typically 15 digits, but may be more in some cases. See https://www.exploringbinary.com/decimal-precision-of-binary-floating-point-numbers/ for more information.

For slightly faster conversion, use NewFromFloatWithExponent where you can specify the precision in absolute terms.

NOTE: this will panic on NaN, +/-inf

func NewFromFloat32 

func NewFromFloat32(value float32) Decimal

NewFromFloat32 converts a float32 to Decimal.

The converted number will contain the number of significant digits that can be represented in a float with reliable roundtrip. This is typically 6-8 digits depending on the input. See https://www.exploringbinary.com/decimal-precision-of-binary-floating-point-numbers/ for more information.

For slightly faster conversion, use NewFromFloatWithExponent where you can specify the precision in absolute terms.

NOTE: this will panic on NaN, +/-inf

func NewFromFloatWithExponent 

func NewFromFloatWithExponent(value float64, exp int32) Decimal

NewFromFloatWithExponent converts a float64 to Decimal, with an arbitrary number of fractional digits.

Example: 

NewFromFloatWithExponent(123.456, -2).String() // output: "123.46"

func NewFromFormattedString added in v1.5.2 

func NewFromFormattedString(value string, replRegexp *regexp.Regexp) (Decimal, error)

NewFromFormattedString returns a new Decimal from a formatted string representation. The second argument - replRegexp, is a regular expression that is used to find characters that should be removed from given decimal string representation. All matched characters will be replaced with an empty string.

Example: 

r := regexp.MustCompile("[$,]")
d1, err := NewFromFormattedString("$5,125.99", r)

r2 := regexp.MustCompile("[_]")
d2, err := NewFromFormattedString("1_000_000", r2)

r3 := regexp.MustCompile("[USD\\s]")
d3, err := NewFromFormattedString("5000 USD", r3)

func NewFromInt 

func NewFromInt(value int64) Decimal

NewFromInt converts a int64 to Decimal.

Example: 

NewFromInt(123).String() // output: "123"
NewFromInt(-10).String() // output: "-10"

func NewFromInt32 

func NewFromInt32(value int32) Decimal

NewFromInt32 converts a int32 to Decimal.

Example: 

NewFromInt(123).String() // output: "123"
NewFromInt(-10).String() // output: "-10"

func NewFromString 

func NewFromString(value string) (Decimal, error)

NewFromString returns a new Decimal from a string representation. Trailing zeroes are not trimmed.

Example: 

d, err := NewFromString("-123.45")
d2, err := NewFromString(".0001")
d3, err := NewFromString("1.47000")

func RequireFromString 

func RequireFromString(value string) Decimal

RequireFromString returns a new Decimal from a string representation or panics if NewFromString would have returned an error.

Example: 

d := RequireFromString("-123.45")
d2 := RequireFromString(".0001")

func Sum 

func Sum(first Decimal, rest ...Decimal) Decimal

Sum returns the combined total of the provided first and rest Decimals

func (Decimal) Abs 

func (d Decimal) Abs() Decimal

Abs returns the absolute value of the decimal.

func (Decimal) Add 

func (d Decimal) Add(d2 Decimal) Decimal

Add returns d + d2.

func (Decimal) Atan 

func (d Decimal) Atan() Decimal

Atan returns the arctangent, in radians, of x.

func (Decimal) BigFloat 

func (d Decimal) BigFloat() *big.Float

BigFloat returns decimal as BigFloat. Be aware that casting decimal to BigFloat might cause a loss of precision.

func (Decimal) BigInt 

func (d Decimal) BigInt() *big.Int

BigInt returns integer component of the decimal as a BigInt.

func (Decimal) Ceil 

func (d Decimal) Ceil() Decimal

Ceil returns the nearest integer value greater than or equal to d.

func (Decimal) Cmp 

func (d Decimal) Cmp(d2 Decimal) int

Cmp compares the numbers represented by d and d2 and returns: 

-1 if d <  d2
 0 if d == d2
+1 if d >  d2

func (Decimal) Coefficient 

func (d Decimal) Coefficient() *big.Int

Coefficient returns the coefficient of the decimal. It is scaled by 10^Exponent()

func (Decimal) CoefficientInt64 added in v1.5.2 

func (d Decimal) CoefficientInt64() int64

CoefficientInt64 returns the coefficient of the decimal as int64. It is scaled by 10^Exponent() If coefficient cannot be represented in an int64, the result will be undefined.

func (Decimal) Copy added in v1.5.2 

func (d Decimal) Copy() Decimal

Copy returns a copy of decimal with the same value and exponent, but a different pointer to value.

func (Decimal) Cos 

func (d Decimal) Cos() Decimal

Cos returns the cosine of the radian argument x.

func (Decimal) Div 

func (d Decimal) Div(d2 Decimal) Decimal

Div returns d / d2. If it doesn't divide exactly, the result will have DivisionPrecision digits after the decimal point.

func (Decimal) DivRound 

func (d Decimal) DivRound(d2 Decimal, precision int32) Decimal

DivRound divides and rounds to a given precision i.e. to an integer multiple of 10^(-precision) 

for a positive quotient digit 5 is rounded up, away from 0
if the quotient is negative then digit 5 is rounded down, away from 0

Note that precision<0 is allowed as input.

func (Decimal) Equal 

func (d Decimal) Equal(d2 Decimal) bool

Equal returns whether the numbers represented by d and d2 are equal.

func (Decimal) Equals 

func (d Decimal) Equals(d2 Decimal) bool

Equals is deprecated, please use Equal method instead

func (Decimal) ExpHullAbrham added in v1.5.2 

func (d Decimal) ExpHullAbrham(overallPrecision uint32) (Decimal, error)

ExpHullAbrham calculates the natural exponent of decimal (e to the power of d) using Hull-Abraham algorithm. OverallPrecision argument specifies the overall precision of the result (integer part + decimal part).

ExpHullAbrham is faster than ExpTaylor for small precision values, but it is much slower for large precision values.

Example: 

NewFromFloat(26.1).ExpHullAbrham(2).String()    // output: "220000000000"
NewFromFloat(26.1).ExpHullAbrham(20).String()   // output: "216314672147.05767284"

func (Decimal) ExpTaylor added in v1.5.2 

func (d Decimal) ExpTaylor(precision int32) (Decimal, error)

ExpTaylor calculates the natural exponent of decimal (e to the power of d) using Taylor series expansion. Precision argument specifies how precise the result must be (number of digits after decimal point). Negative precision is allowed.

ExpTaylor is much faster for large precision values than ExpHullAbrham.

Example: 

d, err := NewFromFloat(26.1).ExpTaylor(2).String()
d.String()  // output: "216314672147.06"

NewFromFloat(26.1).ExpTaylor(20).String()
d.String()  // output: "216314672147.05767284062928674083"

NewFromFloat(26.1).ExpTaylor(-10).String()
d.String()  // output: "220000000000"

func (Decimal) Exponent 

func (d Decimal) Exponent() int32

Exponent returns the exponent, or scale component of the decimal.

func (Decimal) Float64 

func (d Decimal) Float64() (f float64, exact bool)

Float64 returns the nearest float64 value for d and a bool indicating whether f represents d exactly. For more details, see the documentation for big.Rat.Float64

func (Decimal) Floor 

func (d Decimal) Floor() Decimal

Floor returns the nearest integer value less than or equal to d.

func (*Decimal) GobDecode 

func (d *Decimal) GobDecode(data []byte) error

GobDecode implements the gob.GobDecoder interface for gob serialization.

func (Decimal) GobEncode 

func (d Decimal) GobEncode() ([]byte, error)

GobEncode implements the gob.GobEncoder interface for gob serialization.

func (Decimal) GreaterThan 

func (d Decimal) GreaterThan(d2 Decimal) bool

GreaterThan (GT) returns true when d is greater than d2.

func (Decimal) GreaterThanOrEqual 

func (d Decimal) GreaterThanOrEqual(d2 Decimal) bool

GreaterThanOrEqual (GTE) returns true when d is greater than or equal to d2.

func (Decimal) InexactFloat64 added in v1.5.2 

func (d Decimal) InexactFloat64() float64

InexactFloat64 returns the nearest float64 value for d. It doesn't indicate if the returned value represents d exactly.

func (Decimal) IntPart 

func (d Decimal) IntPart() int64

IntPart returns the integer component of the decimal.

func (Decimal) IsInteger added in v1.5.2 

func (d Decimal) IsInteger() bool

IsInteger returns true when decimal can be represented as an integer value, otherwise, it returns false.

func (Decimal) IsNegative 

func (d Decimal) IsNegative() bool

IsNegative return 

true if d < 0
false if d == 0
false if d > 0

func (Decimal) IsPositive 

func (d Decimal) IsPositive() bool

IsPositive return 

true if d > 0
false if d == 0
false if d < 0

func (Decimal) IsZero 

func (d Decimal) IsZero() bool

IsZero return 

true if d == 0
false if d > 0
false if d < 0

func (Decimal) LessThan 

func (d Decimal) LessThan(d2 Decimal) bool

LessThan (LT) returns true when d is less than d2.

func (Decimal) LessThanOrEqual 

func (d Decimal) LessThanOrEqual(d2 Decimal) bool

LessThanOrEqual (LTE) returns true when d is less than or equal to d2.

func (Decimal) MarshalBinary 

func (d Decimal) MarshalBinary() (data []byte, err error)

MarshalBinary implements the encoding.BinaryMarshaler interface.

func (Decimal) MarshalJSON 

func (d Decimal) MarshalJSON() ([]byte, error)

MarshalJSON implements the json.Marshaler interface.

func (Decimal) MarshalText 

func (d Decimal) MarshalText() (text []byte, err error)

MarshalText implements the encoding.TextMarshaler interface for XML serialization.

func (Decimal) Mod 

func (d Decimal) Mod(d2 Decimal) Decimal

Mod returns d % d2.

func (Decimal) Mul 

func (d Decimal) Mul(d2 Decimal) Decimal

Mul returns d * d2.

func (Decimal) Neg 

func (d Decimal) Neg() Decimal

Neg returns -d.

func (Decimal) NumDigits added in v1.5.2 

func (d Decimal) NumDigits() int

NumDigits returns the number of digits of the decimal coefficient (d.Value) Note: Current implementation is extremely slow for large decimals and/or decimals with large fractional part

func (Decimal) Pow 

func (d Decimal) Pow(d2 Decimal) Decimal

Pow returns d to the power d2

func (Decimal) QuoRem 

func (d Decimal) QuoRem(d2 Decimal, precision int32) (Decimal, Decimal)

QuoRem does division with remainder d.QuoRem(d2,precision) returns quotient q and remainder r such that 

d = d2 * q + r, q an integer multiple of 10^(-precision)
0 <= r < abs(d2) * 10 ^(-precision) if d>=0
0 >= r > -abs(d2) * 10 ^(-precision) if d<0

Note that precision<0 is allowed as input.

func (Decimal) Rat 

func (d Decimal) Rat() *big.Rat

Rat returns a rational number representation of the decimal.

func (Decimal) Round 

func (d Decimal) Round(places int32) Decimal

Round rounds the decimal to places decimal places. If places < 0, it will round the integer part to the nearest 10^(-places).

Example: 

NewFromFloat(5.45).Round(1).String() // output: "5.5"
NewFromFloat(545).Round(-1).String() // output: "550"

func (Decimal) RoundBank 

func (d Decimal) RoundBank(places int32) Decimal

RoundBank rounds the decimal to places decimal places. If the final digit to round is equidistant from the nearest two integers the rounded value is taken as the even number

If places < 0, it will round the integer part to the nearest 10^(-places).

Examples: 

NewFromFloat(5.45).RoundBank(1).String() // output: "5.4"
NewFromFloat(545).RoundBank(-1).String() // output: "540"
NewFromFloat(5.46).RoundBank(1).String() // output: "5.5"
NewFromFloat(546).RoundBank(-1).String() // output: "550"
NewFromFloat(5.55).RoundBank(1).String() // output: "5.6"
NewFromFloat(555).RoundBank(-1).String() // output: "560"

func (Decimal) RoundCash 

func (d Decimal) RoundCash(interval uint8) Decimal

RoundCash aka Cash/Penny/öre rounding rounds decimal to a specific interval. The amount payable for a cash transaction is rounded to the nearest multiple of the minimum currency unit available. The following intervals are available: 5, 10, 25, 50 and 100; any other number throws a panic. 

  5:   5 cent rounding 3.43 => 3.45
 10:  10 cent rounding 3.45 => 3.50 (5 gets rounded up)
 25:  25 cent rounding 3.41 => 3.50
 50:  50 cent rounding 3.75 => 4.00
100: 100 cent rounding 3.50 => 4.00

For more details: https://en.wikipedia.org/wiki/Cash_rounding

func (Decimal) RoundCeil added in v1.5.2 

func (d Decimal) RoundCeil(places int32) Decimal

RoundCeil rounds the decimal towards +infinity.

Example: 

NewFromFloat(545).RoundCeil(-2).String()   // output: "600"
NewFromFloat(500).RoundCeil(-2).String()   // output: "500"
NewFromFloat(1.1001).RoundCeil(2).String() // output: "1.11"
NewFromFloat(-1.454).RoundCeil(1).String() // output: "-1.5"

func (Decimal) RoundDown added in v1.5.2 

func (d Decimal) RoundDown(places int32) Decimal

RoundDown rounds the decimal towards zero.

Example: 

NewFromFloat(545).RoundDown(-2).String()   // output: "500"
NewFromFloat(-500).RoundDown(-2).String()   // output: "-500"
NewFromFloat(1.1001).RoundDown(2).String() // output: "1.1"
NewFromFloat(-1.454).RoundDown(1).String() // output: "-1.5"

func (Decimal) RoundFloor added in v1.5.2 

func (d Decimal) RoundFloor(places int32) Decimal

RoundFloor rounds the decimal towards -infinity.

Example: 

NewFromFloat(545).RoundFloor(-2).String()   // output: "500"
NewFromFloat(-500).RoundFloor(-2).String()   // output: "-500"
NewFromFloat(1.1001).RoundFloor(2).String() // output: "1.1"
NewFromFloat(-1.454).RoundFloor(1).String() // output: "-1.4"

func (Decimal) RoundUp added in v1.5.2 

func (d Decimal) RoundUp(places int32) Decimal

RoundUp rounds the decimal away from zero.

Example: 

NewFromFloat(545).RoundUp(-2).String()   // output: "600"
NewFromFloat(500).RoundUp(-2).String()   // output: "500"
NewFromFloat(1.1001).RoundUp(2).String() // output: "1.11"
NewFromFloat(-1.454).RoundUp(1).String() // output: "-1.4"

func (*Decimal) Scan 

func (d *Decimal) Scan(value interface{}) error

Scan implements the sql.Scanner interface for database deserialization.

func (Decimal) Shift 

func (d Decimal) Shift(shift int32) Decimal

Shift shifts the decimal in base 10. It shifts left when shift is positive and right if shift is negative. In simpler terms, the given value for shift is added to the exponent of the decimal.

func (Decimal) Sign 

func (d Decimal) Sign() int

Sign returns: 

-1 if d <  0
 0 if d == 0
+1 if d >  0

func (Decimal) Sin 

func (d Decimal) Sin() Decimal

Sin returns the sine of the radian argument x.

func (Decimal) String 

func (d Decimal) String() string

String returns the string representation of the decimal with the fixed point.

Example: 

d := New(-12345, -3)
println(d.String())

Output: 

-12.345

func (Decimal) StringFixed 

func (d Decimal) StringFixed(places int32) string

StringFixed returns a rounded fixed-point string with places digits after the decimal point.

Example: 

NewFromFloat(0).StringFixed(2) // output: "0.00"
NewFromFloat(0).StringFixed(0) // output: "0"
NewFromFloat(5.45).StringFixed(0) // output: "5"
NewFromFloat(5.45).StringFixed(1) // output: "5.5"
NewFromFloat(5.45).StringFixed(2) // output: "5.45"
NewFromFloat(5.45).StringFixed(3) // output: "5.450"
NewFromFloat(545).StringFixed(-1) // output: "550"

func (Decimal) StringFixedBank 

func (d Decimal) StringFixedBank(places int32) string

StringFixedBank returns a banker rounded fixed-point string with places digits after the decimal point.

Example: 

NewFromFloat(0).StringFixedBank(2) // output: "0.00"
NewFromFloat(0).StringFixedBank(0) // output: "0"
NewFromFloat(5.45).StringFixedBank(0) // output: "5"
NewFromFloat(5.45).StringFixedBank(1) // output: "5.4"
NewFromFloat(5.45).StringFixedBank(2) // output: "5.45"
NewFromFloat(5.45).StringFixedBank(3) // output: "5.450"
NewFromFloat(545).StringFixedBank(-1) // output: "540"

func (Decimal) StringFixedCash 

func (d Decimal) StringFixedCash(interval uint8) string

StringFixedCash returns a Swedish/Cash rounded fixed-point string. For more details see the documentation at function RoundCash.

func (Decimal) StringScaled 

func (d Decimal) StringScaled(exp int32) string

StringScaled first scales the decimal then calls .String() on it. NOTE: buggy, unintuitive, and DEPRECATED! Use StringFixed instead.

func (Decimal) Sub 

func (d Decimal) Sub(d2 Decimal) Decimal

Sub returns d - d2.

func (Decimal) Tan 

func (d Decimal) Tan() Decimal

Tan returns the tangent of the radian argument x.

func (Decimal) Truncate 

func (d Decimal) Truncate(precision int32) Decimal

Truncate truncates off digits from the number, without rounding.

NOTE: precision is the last digit that will not be truncated (must be >= 0).

Example: 

decimal.NewFromString("123.456").Truncate(2).String() // "123.45"

func (*Decimal) UnmarshalBinary 

func (d *Decimal) UnmarshalBinary(data []byte) error

UnmarshalBinary implements the encoding.BinaryUnmarshaler interface. As a string representation is already used when encoding to text, this method stores that string as []byte

func (*Decimal) UnmarshalJSON 

func (d *Decimal) UnmarshalJSON(decimalBytes []byte) error

UnmarshalJSON implements the json.Unmarshaler interface.

func (*Decimal) UnmarshalText 

func (d *Decimal) UnmarshalText(text []byte) error

UnmarshalText implements the encoding.TextUnmarshaler interface for XML deserialization.

func (Decimal) Value 

func (d Decimal) Value() (driver.Value, error)

Value implements the driver.Valuer interface for database serialization.

type NullDecimal 

type NullDecimal struct {
	Decimal Decimal
	Valid   bool
}

NullDecimal represents a nullable decimal with compatibility for scanning null values from the database.

func NewNullDecimal added in v1.5.2 

func NewNullDecimal(d Decimal) NullDecimal

func (NullDecimal) MarshalJSON 

func (d NullDecimal) MarshalJSON() ([]byte, error)

MarshalJSON implements the json.Marshaler interface.

func (NullDecimal) MarshalText added in v1.5.2 

func (d NullDecimal) MarshalText() (text []byte, err error)

MarshalText implements the encoding.TextMarshaler interface for XML serialization.

func (*NullDecimal) Scan 

func (d *NullDecimal) Scan(value interface{}) error

Scan implements the sql.Scanner interface for database deserialization.

func (*NullDecimal) UnmarshalJSON 

func (d *NullDecimal) UnmarshalJSON(decimalBytes []byte) error

UnmarshalJSON implements the json.Unmarshaler interface.

func (*NullDecimal) UnmarshalText added in v1.5.2 

func (d *NullDecimal) UnmarshalText(text []byte) error

UnmarshalText implements the encoding.TextUnmarshaler interface for XML deserialization

func (NullDecimal) Value 

func (d NullDecimal) Value() (driver.Value, error)

Value implements the driver.Valuer interface for database serialization.

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