README
¶
Summary
A fixed place numeric library designed for performance.
All numbers have a fixed 7 decimal places, and the maximum permitted value is +- 99999999999, or just under 100 billion.
The library is safe for concurrent use. It has built-in support for binary and json marshalling.
It is ideally suited for high performance trading financial systems. All common math operations are completed with 0 allocs.
Design Goals
Primarily developed to improve performance in go-trader. Using Fixed rather than decimal.Decimal improves the performance by over 20%, and a lot less GC activity as well. You can review these changes under the 'fixed' branch.
If you review the go-trader code, you will quickly see that I use dot imports for the fixed and common packages. Since this is a "business/user" app and not systems code, this provides 2 major benefits: less verbose code, and I can easily change the implementation of Fixed without changing lots of LOC - just the import statement, and some of the wrapper methods in common.
The fixed.Fixed API uses NaN for reporting errors in the common case, since often code is chained like:
result := someFixed.Mul(NewS("123.50"))
and this would be a huge pain with error handling. Since all operations involving a NaN result in a NaN, any errors quickly surface anyway.
Performance
BenchmarkAddFixed-2 2000000000 0.85 ns/op 0 B/op 0 allocs/op BenchmarkAddDecimal-2 3000000 472 ns/op 400 B/op 10 allocs/op BenchmarkAddBigInt-2 100000000 18.8 ns/op 0 B/op 0 allocs/op BenchmarkAddBigFloat-2 20000000 109 ns/op 48 B/op 1 allocs/op BenchmarkMulFixed-2 200000000 6.14 ns/op 0 B/op 0 allocs/op BenchmarkMulDecimal-2 20000000 96.0 ns/op 80 B/op 2 allocs/op BenchmarkMulBigInt-2 100000000 22.2 ns/op 0 B/op 0 allocs/op BenchmarkMulBigFloat-2 30000000 50.9 ns/op 0 B/op 0 allocs/op BenchmarkDivFixed-2 100000000 19.8 ns/op 0 B/op 0 allocs/op BenchmarkDivDecimal-2 1000000 1206 ns/op 928 B/op 22 allocs/op BenchmarkDivBigInt-2 20000000 67.6 ns/op 48 B/op 1 allocs/op BenchmarkDivBigFloat-2 10000000 148 ns/op 64 B/op 2 allocs/op BenchmarkCmpFixed-2 2000000000 0.28 ns/op 0 B/op 0 allocs/op BenchmarkCmpDecimal-2 100000000 10.8 ns/op 0 B/op 0 allocs/op BenchmarkCmpBigInt-2 200000000 8.10 ns/op 0 B/op 0 allocs/op BenchmarkCmpBigFloat-2 200000000 8.39 ns/op 0 B/op 0 allocs/op BenchmarkStringFixed-2 20000000 76.1 ns/op 32 B/op 1 allocs/op BenchmarkStringNFixed-2 20000000 72.9 ns/op 32 B/op 1 allocs/op BenchmarkStringDecimal-2 5000000 328 ns/op 144 B/op 5 allocs/op BenchmarkStringBigInt-2 10000000 212 ns/op 80 B/op 3 allocs/op BenchmarkStringBigFloat-2 3000000 568 ns/op 272 B/op 8 allocs/op BenchmarkWriteTo-2 20000000 69.9 ns/op 27 B/op 0 allocs/op
The "decimal" above is the common shopspring decimal library
Compatibility with SQL drivers
By default Fixed implements decomposer.Decimal interface for database
drivers that support it. To use sql.Scanner and driver.Valuer
implementation flag sql_scanner must be specified on build.
Documentation
¶
Index ¶
- Constants
- Variables
- type Fixed
- func (f Fixed) Abs() Fixed
- func (f Fixed) Add(f0 Fixed) Fixed
- func (f Fixed) Cmp(f0 Fixed) int
- func (f *Fixed) Compose(form byte, negative bool, coefficient []byte, exponent int32) (err error)
- func (f Fixed) Decompose(buf []byte) (form byte, negative bool, coefficient []byte, exponent int32)
- func (f Fixed) Div(f0 Fixed) Fixed
- func (f Fixed) Equal(f0 Fixed) bool
- func (f Fixed) Float() float64
- func (f Fixed) Frac() float64
- func (f Fixed) GreaterThan(f0 Fixed) bool
- func (f Fixed) GreaterThanOrEqual(f0 Fixed) bool
- func (f Fixed) Int() int64
- func (f Fixed) IsNaN() bool
- func (f Fixed) IsZero() bool
- func (f Fixed) LessThan(f0 Fixed) bool
- func (f Fixed) LessThanOrEqual(f0 Fixed) bool
- func (f Fixed) MarshalBinary() (data []byte, err error)
- func (f Fixed) MarshalJSON() ([]byte, error)
- func (f Fixed) Mul(f0 Fixed) Fixed
- func (f Fixed) Round(n int) Fixed
- func (f Fixed) Sign() int
- func (f Fixed) String() string
- func (f Fixed) StringN(decimals int) string
- func (f Fixed) Sub(f0 Fixed) Fixed
- func (f *Fixed) UnmarshalBinary(data []byte) error
- func (f *Fixed) UnmarshalJSON(bytes []byte) error
- func (f Fixed) WriteTo(w io.ByteWriter) error
Constants ¶
const MAX = float64(99999999999.9999999)
Variables ¶
var NaN = Fixed{/* contains filtered or unexported fields */}
var ZERO = Fixed{/* contains filtered or unexported fields */}
Functions ¶
This section is empty.
Types ¶
type Fixed ¶
type Fixed struct {
// contains filtered or unexported fields
}
Fixed is a fixed precision 38.24 number (supports 11.7 digits). It supports NaN.
func MustParse ¶
MustParse creates a new Fixed from a string, and panics if the string could not be parsed
func NewI ¶
NewI creates a Fixed for an integer, moving the decimal point n places to the left For example, NewI(123,1) becomes 12.3. If n > 7, the value is truncated
func NewSErr ¶
NewSErr creates a new Fixed from a string, returning NaN, and error if the string could not be parsed
func Parse ¶
Parse creates a new Fixed from a string, returning NaN, and error if the string could not be parsed. Same as NewSErr but more standard naming
func ReadFrom ¶
func ReadFrom(r io.ByteReader) (Fixed, error)
ReadFrom reads a Fixed from an io.Reader
func (Fixed) Cmp ¶
Cmp compares two Fixed. If f == f0, return 0. If f > f0, return 1. If f < f0, return -1. If both are NaN, return 0. If f is NaN, return 1. If f0 is NaN, return -1
func (*Fixed) Compose ¶
Compose sets the internal decimal value from parts. If the value cannot be represented then an error should be returned.
func (Fixed) Decompose ¶
Decompose returns the internal decimal state into parts. If the provided buf has sufficient capacity, buf may be returned as the coefficient with the value set and length set as appropriate.
func (Fixed) Equal ¶
Equal returns true if the f == f0. If either operand is NaN, false is returned. Use IsNaN() to test for NaN
func (Fixed) GreaterThanOrEqual ¶
GreaterThaOrEqual tests Cmp() for 1 or 0
func (Fixed) LessThanOrEqual ¶
LessThan tests Cmp() for -1 or 0
func (Fixed) MarshalBinary ¶
MarshalBinary implements the encoding.BinaryMarshaler interface.
func (Fixed) MarshalJSON ¶
MarshalJSON implements the json.Marshaler interface.
func (Fixed) Mul ¶
Mul multiplies f by f0 returning a Fixed. If either operand is NaN, NaN is returned
func (Fixed) StringN ¶
StringN converts a Fixed to a String with a specified number of decimal places, truncating as required
func (Fixed) Sub ¶
Sub subtracts f0 from f producing a Fixed. If either operand is NaN, NaN is returned
func (*Fixed) UnmarshalBinary ¶
UnmarshalBinary implements the encoding.BinaryUnmarshaler interface
func (*Fixed) UnmarshalJSON ¶
UnmarshalJSON implements the json.Unmarshaler interface.
Source Files
Directories