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native square root function for decimal
This commit is contained in:
Geert van Kempen
parent
53965de086
commit
3954520093
2 changed files with 65 additions and 35 deletions
68
numbers.go
68
numbers.go
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@ -1,99 +1,97 @@
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package common
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import "github.com/shopspring/decimal"
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package decimal
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// MinusOne defines value -1 in decimal format
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var MinusOne = decimal.New(-1, 0)
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var MinusOne = New(-1, 0)
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// OneTenth defines value 0.1 in decimal format
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var OneTenth = decimal.New(1, -1)
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var OneTenth = New(1, -1)
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// TwoTenth defines value 0.1 in decimal format
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var TwoTenth = decimal.New(2, -1)
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var TwoTenth = New(2, -1)
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// Half defines value 0.5 in decimal format
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var Half = decimal.New(5, -1)
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var Half = New(5, -1)
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// One defines value 1 in decimal format
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var One = decimal.New(1, 0)
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var One = New(1, 0)
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// Two defines value 2 in decimal format
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var Two = decimal.New(2, 0)
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var Two = New(2, 0)
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// Three defines value 3 in decimal format
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var Three = decimal.New(3, 0)
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var Three = New(3, 0)
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// Four defines value 4 in decimal format
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var Four = decimal.New(4, 0)
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var Four = New(4, 0)
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// Five defines value 5 in decimal format
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var Five = decimal.New(5, 0)
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var Five = New(5, 0)
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// Six defines value 6 in decimal format
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var Six = decimal.New(6, 0)
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var Six = New(6, 0)
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// Seven defines value 6 in decimal format
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var Seven = decimal.New(7, 0)
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var Seven = New(7, 0)
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// Eight defines value 8 in decimal format
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var Eight = decimal.New(8, 0)
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var Eight = New(8, 0)
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// Nine defines value 9 in decimal format
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var Nine = decimal.New(9, 0)
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var Nine = New(9, 0)
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// Ten defines value 10 in decimal format
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var Ten = decimal.New(10, 0)
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var Ten = New(10, 0)
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// Twenty defines value 20 in decimal format
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var Twenty = decimal.New(20, 0)
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var Twenty = New(20, 0)
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// Thirty defines value 30 in decimal format
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var Thirty = decimal.New(30, 0)
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var Thirty = New(30, 0)
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// Forty defines value 40 in decimal format
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var Forty = decimal.New(40, 0)
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var Forty = New(40, 0)
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// Fifty defines value 50 in decimal format
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var Fifty = decimal.New(50, 0)
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var Fifty = New(50, 0)
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// Sixty defines value 60 in decimal format
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var Sixty = decimal.New(60, 0)
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var Sixty = New(60, 0)
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// Seventy defines value 70 in decimal format
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var Seventy = decimal.New(70, 0)
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var Seventy = New(70, 0)
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// Eighty defines value 80 in decimal format
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var Eighty = decimal.New(80, 0)
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var Eighty = New(80, 0)
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// Ninty defines value 90 in decimal format
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var Ninty = decimal.New(90, 0)
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var Ninty = New(90, 0)
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// Hundred defines value 100 in decimal format
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var Hundred = decimal.New(100, 0)
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var Hundred = New(100, 0)
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// TwoHundred defines value 200 in decimal format
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var TwoHundred = decimal.New(200, 0)
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var TwoHundred = New(200, 0)
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// ThreeHundred defines value 300 in decimal format
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var ThreeHundred = decimal.New(300, 0)
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var ThreeHundred = New(300, 0)
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// FourHundred defines value 400 in decimal format
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var FourHundred = decimal.New(400, 0)
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var FourHundred = New(400, 0)
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// FiveHundred defines value 500 in decimal format
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var FiveHundred = decimal.New(500, 0)
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var FiveHundred = New(500, 0)
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// SixHundred defines value 600 in decimal format
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var SixHundred = decimal.New(600, 0)
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var SixHundred = New(600, 0)
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// SevenHundred defines value 700 in decimal format
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var SevenHundred = decimal.New(700, 0)
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var SevenHundred = New(700, 0)
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// EightHundred defines value 800 in decimal format
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var EightHundred = decimal.New(800, 0)
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var EightHundred = New(800, 0)
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// NineHundred defines value 900 in decimal format
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var NineHundred = decimal.New(900, 0)
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var NineHundred = New(900, 0)
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// Thousand defines value 100 in decimal format
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var Thousand = decimal.New(1000, 0)
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var Thousand = New(1000, 0)
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32
sqrt.go
Normal file
32
sqrt.go
Normal file
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@ -0,0 +1,32 @@
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package decimal
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const sqrtMaxIter = 10000
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// Sqrt returns the square root of d, the result will have
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// DivisionPrecision digits after the decimal point.
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func (d Decimal) Sqrt() Decimal {
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s, _ := d.SqrtRound(int32(DivisionPrecision))
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return s
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}
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// SqrtRound returns the square root of d, the result will have
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// precision digits after the decimal point. The bool precise returns whether the precision was reached
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func (d Decimal) SqrtRound(precision int32) (Decimal, bool) {
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cutoff := New(1, -precision)
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lo := Zero
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hi := d
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var mid Decimal
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for i := 0; i < sqrtMaxIter; i++ {
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//mid = (lo+hi)/2;
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mid = lo.Add(hi).DivRound(Two, precision)
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if mid.Mul(mid).Sub(d).Abs().LessThan(cutoff) {
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return mid, true
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}
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if mid.Mul(mid).GreaterThan(d) {
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hi = mid
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} else {
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lo = mid
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}
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}
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return mid, false
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}
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