Fixed the NaN numbers in Stochastic Oscillator. (#123)

# Describe Request

Fixed the NaN numbers in Stochastic Oscillator.

Fixed #122 

# Change Type

Bug fix.

helper.go

@@ -290,3 +290,18 @@ func abs(values []float64) []float64 {
 
 	return result
 }
+
+// fillNaNWith fills the NaN values with the given fill value.
+func fillNaNWith(values []float64, fill float64) []float64 {
+	result := make([]float64, len(values))
+
+	for i, value := range values {
+		if math.IsNaN(value) {
+			value = fill
+		}
+
+		result[i] = value
+	}
+
+	return result
+}

momentum_indicators.go

@@ -184,7 +184,7 @@ func StochasticOscillator(high, low, closing []float64) ([]float64, []float64) {
 	lowestLow14 := Min(14, low)
 
 	k := multiplyBy(divide(subtract(closing, lowestLow14), subtract(highestHigh14, lowestLow14)), float64(100))
-	d := Sma(3, k)
+	d := Sma(3, fillNaNWith(k, 0))
 
 	return k, d
 }