Added Round function and unit tests

utils.go

@@ -1,13 +1,14 @@
 package autotrader
 
 import (
+	"math"
 	"os/exec"
 	"runtime"
 
 	"golang.org/x/exp/constraints"
 )
 
-const floatComparisonTolerance = float64(1e-6)
+const float64Tolerance = float64(1e-6)
 
 // Crossover returns true if the latest a value crosses above the latest b value, but only if it just happened. For example, if a series is [1, 2, 3, 4, 5] and b series is [1, 2, 3, 4, 3], then Crossover(a, b) returns false because the latest a value is 5 and the latest b value is 3. However, if a series is [1, 2, 3, 4, 5] and b series is [1, 2, 3, 4, 6], then Crossover(a, b) returns true because the latest a value is 5 and the latest b value is 6
 func Crossover(a, b Series) bool {
@@ -22,8 +23,28 @@ func EasyIndex(i, n int) int {
 	return i
 }
 
+// EqualApprox returns true if a and b are approximately equal. NaN and Inf are handled correctly. The tolerance is 1e-6 or 0.0000001.
 func EqualApprox(a, b float64) bool {
-	return Abs(a-b) < floatComparisonTolerance
+	if math.IsNaN(a) || math.IsNaN(b) {
+		return math.IsNaN(a) && math.IsNaN(b)
+	} else if math.IsInf(a, 1) || math.IsInf(b, 1) {
+		return math.IsInf(a, 1) && math.IsInf(b, 1)
+	} else if math.IsInf(a, -1) || math.IsInf(b, -1) {
+		return math.IsInf(a, -1) && math.IsInf(b, -1)
+	}
+	return math.Abs(a-b) <= float64Tolerance
+}
+
+// Round returns f rounded to d decimal places. d may be negative to round to the left of the decimal point.
+//
+// Examples:
+//
+//	Round(123.456, 0) // 123.0
+//	Round(123.456, 1) // 123.5
+//	Round(123.456, -1) // 120.0
+func Round(f float64, d int) float64 {
+	ratio := math.Pow10(d)
+	return math.Round(f*ratio) / ratio
 }
 
 func Abs[T constraints.Integer | constraints.Float](a T) T {