native square root function for decimal

numbers.go

@@ -1,99 +1,97 @@
-package common
+package decimal
-
-import "github.com/shopspring/decimal"
 
 // MinusOne defines value -1 in decimal format
-var MinusOne = decimal.New(-1, 0)
+var MinusOne = New(-1, 0)
 
 // OneTenth defines value 0.1 in decimal format
-var OneTenth = decimal.New(1, -1)
+var OneTenth = New(1, -1)
 
 // TwoTenth defines value 0.1 in decimal format
-var TwoTenth = decimal.New(2, -1)
+var TwoTenth = New(2, -1)
 
 // Half defines value 0.5 in decimal format
-var Half = decimal.New(5, -1)
+var Half = New(5, -1)
 
 // One defines value 1 in decimal format
-var One = decimal.New(1, 0)
+var One = New(1, 0)
 
 // Two defines value 2 in decimal format
-var Two = decimal.New(2, 0)
+var Two = New(2, 0)
 
 // Three defines value 3 in decimal format
-var Three = decimal.New(3, 0)
+var Three = New(3, 0)
 
 // Four defines value 4 in decimal format
-var Four = decimal.New(4, 0)
+var Four = New(4, 0)
 
 // Five defines value 5 in decimal format
-var Five = decimal.New(5, 0)
+var Five = New(5, 0)
 
 // Six defines value 6 in decimal format
-var Six = decimal.New(6, 0)
+var Six = New(6, 0)
 
 // Seven defines value 6 in decimal format
-var Seven = decimal.New(7, 0)
+var Seven = New(7, 0)
 
 // Eight defines value 8 in decimal format
-var Eight = decimal.New(8, 0)
+var Eight = New(8, 0)
 
 // Nine defines value 9 in decimal format
-var Nine = decimal.New(9, 0)
+var Nine = New(9, 0)
 
 // Ten defines value 10 in decimal format
-var Ten = decimal.New(10, 0)
+var Ten = New(10, 0)
 
 // Twenty defines value 20 in decimal format
-var Twenty = decimal.New(20, 0)
+var Twenty = New(20, 0)
 
 // Thirty defines value 30 in decimal format
-var Thirty = decimal.New(30, 0)
+var Thirty = New(30, 0)
 
 // Forty defines value 40 in decimal format
-var Forty = decimal.New(40, 0)
+var Forty = New(40, 0)
 
 // Fifty defines value 50 in decimal format
-var Fifty = decimal.New(50, 0)
+var Fifty = New(50, 0)
 
 // Sixty defines value 60 in decimal format
-var Sixty = decimal.New(60, 0)
+var Sixty = New(60, 0)
 
 // Seventy defines value 70 in decimal format
-var Seventy = decimal.New(70, 0)
+var Seventy = New(70, 0)
 
 // Eighty defines value 80 in decimal format
-var Eighty = decimal.New(80, 0)
+var Eighty = New(80, 0)
 
 // Ninty defines value 90 in decimal format
-var Ninty = decimal.New(90, 0)
+var Ninty = New(90, 0)
 
 // Hundred defines value 100 in decimal format
-var Hundred = decimal.New(100, 0)
+var Hundred = New(100, 0)
 
 // TwoHundred defines value 200 in decimal format
-var TwoHundred = decimal.New(200, 0)
+var TwoHundred = New(200, 0)
 
 // ThreeHundred defines value 300 in decimal format
-var ThreeHundred = decimal.New(300, 0)
+var ThreeHundred = New(300, 0)
 
 // FourHundred defines value 400 in decimal format
-var FourHundred = decimal.New(400, 0)
+var FourHundred = New(400, 0)
 
 // FiveHundred defines value 500 in decimal format
-var FiveHundred = decimal.New(500, 0)
+var FiveHundred = New(500, 0)
 
 // SixHundred defines value 600 in decimal format
-var SixHundred = decimal.New(600, 0)
+var SixHundred = New(600, 0)
 
 // SevenHundred defines value 700 in decimal format
-var SevenHundred = decimal.New(700, 0)
+var SevenHundred = New(700, 0)
 
 // EightHundred defines value 800 in decimal format
-var EightHundred = decimal.New(800, 0)
+var EightHundred = New(800, 0)
 
 // NineHundred defines value 900 in decimal format
-var NineHundred = decimal.New(900, 0)
+var NineHundred = New(900, 0)
 
 // Thousand defines value 100 in decimal format
-var Thousand = decimal.New(1000, 0)
+var Thousand = New(1000, 0)

sqrt.go

@@ -0,0 +1,32 @@
+package decimal
+
+const sqrtMaxIter = 10000
+
+// Sqrt returns the square root of d, the result will have
+// DivisionPrecision digits after the decimal point.
+func (d Decimal) Sqrt() Decimal {
+	s, _ := d.SqrtRound(int32(DivisionPrecision))
+	return s
+}
+
+// SqrtRound returns the square root of d, the result will have
+// precision digits after the decimal point. The bool precise returns whether the precision was reached
+func (d Decimal) SqrtRound(precision int32) (Decimal, bool) {
+	cutoff := New(1, -precision)
+	lo := Zero
+	hi := d
+	var mid Decimal
+	for i := 0; i < sqrtMaxIter; i++ {
+		//mid = (lo+hi)/2;
+		mid = lo.Add(hi).DivRound(Two, precision)
+		if mid.Mul(mid).Sub(d).Abs().LessThan(cutoff) {
+			return mid, true
+		}
+		if mid.Mul(mid).GreaterThan(d) {
+			hi = mid
+		} else {
+			lo = mid
+		}
+	}
+	return mid, false
+}