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

Calculations/_Updated/TSeries.cs

@@ -0,0 +1,85 @@
+namespace QuanTAlib;
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Data;
+using System.Linq;
+
+/* <summary>
+TSeries is the cornerstone of all QuanTAlib classes.
+    TSeries is a single List of tuples (time, value) and contains several operators, casts, overloads
+    and other helpers that simplify usage of library.
+    Think of TSeries as an equivalent of Numpy array.
+
+        - includes Length property (to mimic array's method)
+        - includes publishing and subscribing methods that attach to events
+
+</summary> */
+public class TSeriesEventArgs : EventArgs {
+	public bool update { get; set; }
+}
+
+public class TSeries : List<(DateTime t, double v)> {
+	public List<DateTime> t => this.Select(item => item.t).ToList();
+	public List<double> v => this.Select(item => item.v).ToList();
+	public (DateTime t, double v) Last => this[^1];
+	public int Length => Count;
+	public string Name { get; set; }
+
+	public TSeries() {
+		this.Name = "data";
+	}
+
+	public TSeries(string Name) {
+		this.Name = Name;
+	}
+
+	public virtual (DateTime t, double v) Add(double v, bool update = false) {
+		var Value = (t: Count == 0 ? DateTime.Today : this[^1].t.AddDays(1), v);
+		return Add(Value, update);
+	}
+
+	public virtual (DateTime t, double v) Add((DateTime t, double v) TValue, bool update = false) {
+		if (update) {
+			this[^1] = TValue;
+		}
+		else {
+			base.Add(TValue);
+		}
+
+		OnEvent(update);
+		return TValue;
+	}
+
+	public virtual (DateTime t, double v) Add(TSeries data) {
+		foreach (var item in data) { Add(item, false); }
+		return data.Last;
+	}
+
+	public void Sub(object source, TSeriesEventArgs e) {
+		var data = (TSeries) source;
+		if (data == null) { return; }
+		foreach (var item in data) { Add(item, update: false); }
+	}
+
+	public delegate void NewEventHandler(object source, TSeriesEventArgs args);
+
+	public event NewEventHandler Pub;
+
+	protected virtual void OnEvent(bool update = false)
+	{
+		Pub?.Invoke(this, new TSeriesEventArgs {update = update});
+	}
+
+	/// common helpers
+	public static void BufferTrim(List<double> buffer, double value, int period, bool update) {
+		if (!update) {
+			buffer.Add(value);
+			if (buffer.Count > period && period > 0) {  buffer.RemoveAt(0); }
+			return;
+		}
+		buffer[^1] = value;
+	}
+	public virtual void Reset() {
+	}
+}