Update RSI_Series to check for period != 0 before calculating RSI

Calculations/_Updated/BIAS_Series.cs

@@ -0,0 +1,75 @@
+namespace QuanTAlib;
+using System;
+
+/* <summary>
+BIAS: Rate of change between the source and a moving average.
+    Bias is a statistical term which means a systematic deviation from the actual value.
+
+BIAS = (close - SMA) / SMA
+       = (close / SMA) - 1
+
+Sources:
+	https://en.wikipedia.org/wiki/Bias_of_an_estimator
+
+</summary> */
+
+public class BIAS_Series : TSeries {
+	protected readonly int _period;
+	protected readonly bool _NaN;
+	protected readonly TSeries _data;
+	private readonly SMA_Series _sma;
+
+	//core constructors
+	public BIAS_Series(int period, bool useNaN) : base() {
+		_period = period;
+		_NaN = useNaN;
+		Name = $"BIAS({period})";
+		_sma = new(period, false);	
+	}
+	public BIAS_Series(TSeries source, int period, bool useNaN) : this(period, useNaN) {
+		_data = source;
+		Name = Name.Substring(0, Name.IndexOf(")")) + $", {(string.IsNullOrEmpty(_data.Name) ? "data" : _data.Name)})";
+		_data.Pub += Sub;
+		Add(_data);
+	}
+	public BIAS_Series() : this(period: 0, useNaN: false) { }
+	public BIAS_Series(int period) : this(period: period, useNaN: false) { }
+	public BIAS_Series(TBars source) : this(source.Close, 0, false) { }
+	public BIAS_Series(TBars source, int period) : this(source.Close, period, false) { }
+	public BIAS_Series(TBars source, int period, bool useNaN) : this(source.Close, period, useNaN) { }
+	public BIAS_Series(TSeries source) : this(source, 0, false) { }
+	public BIAS_Series(TSeries source, int period) : this(source: source, period: period, useNaN: false) { }
+
+	//////////////////
+	// core Add() algo
+	public override (DateTime t, double v) Add((DateTime t, double v) TValue, bool update = false) {
+		var _s = _sma.Add(TValue,update);
+		double _bias = (TValue.v / ((_s.v!=0)?_s.v:1)) - 1;
+
+		var res = (TValue.t, Count < _period - 1 && _NaN ? double.NaN : _bias);
+		return base.Add(res, update);
+	}
+
+	public override (DateTime t, double v) Add(TSeries data) {
+		if (data == null) { return (DateTime.Today, Double.NaN); }
+		foreach (var item in data) { Add(item, false); }
+		return _data.Last;
+	}
+	public new (DateTime t, double v) Add((DateTime t, double v) TValue) {
+		return Add(TValue, false);
+	}
+	public (DateTime t, double v) Add(bool update) {
+		return this.Add(TValue: _data.Last, update: update);
+	}
+	public (DateTime t, double v) Add() {
+		return Add(TValue: _data.Last, update: false);
+	}
+	private new void Sub(object source, TSeriesEventArgs e) {
+		Add(TValue: _data.Last, update: e.update);
+	}
+
+	//reset calculation
+	public override void Reset() {
+		_sma.Reset();
+	}
+}