Made binary search work with the caching. Much faster, very happy with it.

Base/Forms/GraphForm.cs

@@ -1,6 +1,5 @@
 using Graphing.Extensions;
 using Graphing.Graphables;
-using Graphing.Parts;
 using System.Drawing.Drawing2D;
 using System.Text;
 
@@ -170,9 +169,9 @@ public partial class GraphForm : Form
         Invalidate(false);
     }
 
-    public void Graph(Graphable able)
+    public void Graph(params Graphable[] able)
     {
-        ables.Add(able);
+        ables.AddRange(able);
         RegenerateMenuItems();
         Invalidate(false);
     }

Base/Graphable.cs

@@ -29,6 +29,8 @@ public abstract class Graphable
 
     public abstract IEnumerable<IGraphPart> GetItemsToRender(in GraphForm graph);
 
+    public abstract Graphable DeepCopy();
+
     public abstract void EraseCache();
     public abstract long GetCacheBytes();
 }

Base/Graphables/ColumnTable.cs

@@ -0,0 +1,51 @@
+using Graphing.Forms;
+using Graphing.Parts;
+
+namespace Graphing.Graphables;
+
+public class ColumnTable : Graphable
+{
+    private static int tableNum;
+
+    private readonly Dictionary<double, double> tableXY;
+    private readonly double width;
+
+    public ColumnTable(double width, Dictionary<double, double> tableXY)
+    {
+        tableNum++;
+        Name = $"Column Table {tableNum}";
+
+        this.tableXY = tableXY;
+        this.width = width;
+    }
+    public ColumnTable(double step, Equation equation, double min, double max)
+    {
+        Name = $"Column Table for {equation.Name}";
+
+        tableXY = [];
+        EquationDelegate equ = equation.GetDelegate();
+        width = 0.75 * step;
+
+        double minRounded = Math.Round(min / step) * step,
+               maxRounded = Math.Round(max / step) * step;
+        for (double x = minRounded; x <= maxRounded; x += step)
+            tableXY.Add(x, equ(x));
+    }
+
+    public override void EraseCache() { }
+    public override long GetCacheBytes() => 16 * tableXY.Count;
+
+    public override Graphable DeepCopy() => new ColumnTable(width / 0.75, tableXY.ToArray().ToDictionary());
+
+    public override IEnumerable<IGraphPart> GetItemsToRender(in GraphForm graph)
+    {
+        List<IGraphPart> items = [];
+        foreach (KeyValuePair<double, double> col in tableXY)
+        {
+            items.Add(GraphRectangle.FromSize(new Float2(col.Key, col.Value / 2),
+                                              new Float2(width, col.Value)));
+        }
+
+        return items;
+    }
+}

Base/Graphables/Equation.cs

@@ -8,7 +8,6 @@ public class Equation : Graphable
     private static int equationNum;
 
     private readonly EquationDelegate equ;
-
     private readonly List<Float2> cache;
 
     public Equation(EquationDelegate equ)
@@ -42,9 +41,6 @@ public class Equation : Graphable
             previousX = currentX;
             previousY = currentY;
         }
-
-        // if (addedToDictionary) cache.Sort((a, b) => a.y.CompareTo(b.y)); todo: not required until binary search
-
         return lines;
     }
 
@@ -58,34 +54,47 @@ public class Equation : Graphable
         else
         {
             double result = equ(x);
-            cache.Add(new(x, result));
-            // TODO: Rather than sorting the whole list when we add a single number,
-            //       we could just insert it in its proper place.
+            cache.Insert(index + 1, new(x, result));
             return result;
         }
     }
 
+    // Pretty sure this works. Certainly works pretty well with "hard-to-compute"
+    // equations.
     private (double dist, double y, int index) NearestCachedPoint(double x)
     {
-        // TODO: Replace with a binary search system.
-        double closestDist = double.PositiveInfinity;
-        double closest = 0;
-        int closestIndex = -1;
-
-        for (int i = 0; i < cache.Count; i++)
+        if (cache.Count == 0) return (double.PositiveInfinity, double.NaN, -1);
+        else if (cache.Count == 1)
         {
-            double dist = Math.Abs(x - cache[i].x);
-            if (dist < closestDist)
-            {
-                closestDist = dist;
-                closest = cache[i].y;
-                closestIndex = i;
-            }
+            Float2 single = cache[0];
+            return (Math.Abs(single.x - x), single.y, 0);
         }
+        else
+        {
+            int boundA = 0, boundB = cache.Count;
+            do
+            {
+                int boundC = (boundA + boundB) / 2;
+                Float2 pointC = cache[boundC];
 
-        return (closestDist, closest, closestIndex);
+                if (pointC.x == x) return (0, pointC.y, boundC);
+                else if (pointC.x > x)
+                {
+                    boundA = boundC;
+                }
+                else // pointC.x < x
+                {
+                    boundB = boundC;
+                }
+
+            } while (boundB - boundA > 1);
+
+            return (Math.Abs(cache[boundA].x - x), cache[boundA].y, boundA);
+        }
     }
 
+    public override Graphable DeepCopy() => new Equation(equ);
+
     public override long GetCacheBytes() => cache.Count * 16;
 }
 

Base/Graphables/SlopeField.cs

@@ -1,6 +1,5 @@
 using Graphing.Forms;
 using Graphing.Parts;
-using static System.Windows.Forms.LinkLabel;
 
 namespace Graphing.Graphables;
 
@@ -9,7 +8,7 @@ public class SlopeField : Graphable
     private static int slopeFieldNum;
 
     private readonly SlopeFieldsDelegate equ;
-    private readonly double detail;
+    private readonly int detail;
 
     private readonly List<(Float2, GraphLine)> cache;
 
@@ -71,6 +70,8 @@ public class SlopeField : Graphable
         return result;
     }
 
+    public override Graphable DeepCopy() => new SlopeField(detail, equ);
+
     public override void EraseCache() => cache.Clear();
     public override long GetCacheBytes() => cache.Count * 48;
 }

Base/Graphables/TangentLine.cs

@@ -7,6 +7,7 @@ public class TangentLine : Graphable
 {
     public double Position { get; set; }
 
+    private readonly Equation parent;
     private readonly EquationDelegate parentEqu;
 
     private readonly double length;
@@ -18,13 +19,14 @@ public class TangentLine : Graphable
         parentEqu = parent.GetDelegate();
         Position = position;
         this.length = length;
+        this.parent = parent;
     }
 
     public override IEnumerable<IGraphPart> GetItemsToRender(in GraphForm graph)
     {
         Float2 point = new(Position, parentEqu(Position));
         return [MakeSlopeLine(point, DerivativeAtPoint(Position)),
-                new GraphCircle(point, 8)];
+                new GraphUiCircle(point, 8)];
     }
     private GraphLine MakeSlopeLine(Float2 position, double slope)
     {
@@ -42,6 +44,8 @@ public class TangentLine : Graphable
         return (parentEqu(x + step) - parentEqu(x)) / step;
     }
 
+    public override Graphable DeepCopy() => new TangentLine(length, Position, parent);
+
     public override void EraseCache() { }
     public override long GetCacheBytes() => 0;
 }

Base/Parts/GraphLine.cs

@@ -20,8 +20,8 @@ public record struct GraphLine : IGraphPart
 
     public readonly void Render(in GraphForm form, in Graphics g, in Brush brush)
     {
-        if (!double.IsNormal(a.x) || !double.IsNormal(a.y) ||
-            !double.IsNormal(b.x) || !double.IsNormal(b.y)) return;
+        if (!double.IsFinite(a.x) || !double.IsFinite(a.y) ||
+            !double.IsFinite(b.x) || !double.IsFinite(b.y)) return;
 
         Int2 start = form.GraphSpaceToScreenSpace(a),
              end = form.GraphSpaceToScreenSpace(b);

Base/Parts/GraphRectangle.cs

@@ -0,0 +1,45 @@
+using Graphing.Forms;
+
+namespace Graphing.Parts;
+
+public struct GraphRectangle : IGraphPart
+{
+    public Float2 min, max;
+
+    public GraphRectangle()
+    {
+        min = new();
+        max = new();
+    }
+    
+    public static GraphRectangle FromSize(Float2 center, Float2 size) => new()
+    {
+        min = new(center.x - size.x / 2,
+                  center.y - size.y / 2),
+        max = new(center.x + size.x / 2,
+                  center.y + size.y / 2)
+    };
+    public static GraphRectangle FromRange(Float2 min, Float2 max) => new()
+    {
+        min = min,
+        max = max
+    };
+
+    public void Render(in GraphForm form, in Graphics g, in Brush brush)
+    {
+        if (!double.IsFinite(max.x) || !double.IsFinite(max.y) ||
+            !double.IsFinite(min.x) || !double.IsFinite(min.y)) return;
+
+        if (min.x > max.x) (min.x, max.x) = (max.x, min.x);
+        if (min.y > max.y) (min.y, max.y) = (max.y, min.y);
+
+        Int2 start = form.GraphSpaceToScreenSpace(min),
+             end = form.GraphSpaceToScreenSpace(max);
+
+        Int2 size = new(end.x - start.x + 1,
+                        start.y - end.y);
+
+        if (size.x == 0 || size.y == 0) return;
+        g.FillRectangle(brush, new Rectangle(start.x, end.y, size.x, size.y));
+    }
+}

Base/Parts/GraphUiCircle.cs

@@ -2,17 +2,17 @@
 
 namespace Graphing.Parts;
 
-public record struct GraphCircle : IGraphPart
+public record struct GraphUiCircle : IGraphPart
 {
     public Float2 center;
     public int radius;
 
-    public GraphCircle()
+    public GraphUiCircle()
     {
         center = new();
         radius = 1;
     }
-    public GraphCircle(Float2 center, int radius)
+    public GraphUiCircle(Float2 center, int radius)
     {
         this.center = center;
         this.radius = radius;
@@ -20,8 +20,8 @@ public record struct GraphCircle : IGraphPart
 
     public readonly void Render(in GraphForm form, in Graphics g, in Brush brush)
     {
-        if (!double.IsNormal(center.x) || !double.IsNormal(center.y) ||
-            !double.IsNormal(radius)) return;
+        if (!double.IsFinite(center.x) || !double.IsFinite(center.y) ||
+            !double.IsFinite(radius) || radius == 0) return;
 
         Int2 centerPix = form.GraphSpaceToScreenSpace(center);
         g.FillEllipse(brush, new Rectangle(new Point(centerPix.x - radius,

Testing/Program.cs

@@ -14,17 +14,18 @@ internal static class Program
 
         GraphForm graph = new("One Of The Graphing Calculators Of All Time");
 
-        Equation equ = new(x => x * x);
-        TangentLine tangent = new(5, 2, equ);
-
+        Equation equ = new(x =>
+        {
+            // Demonstrate the caching abilities of the software.
+            // This extra waiting is done every time the form requires a
+            // calculation done. At the start, it'll be laggy, but as you
+            // move around and zoom in, more pieces are cached, and when
+            // you reset, the viewport will be a lot less laggy.
+            for (int i = 0; i < 1_000_000; i++) ;
+            return x * x;
+        });
         graph.Graph(equ);
-        graph.Graph(tangent);
 
         Application.Run(graph);
     }
-
-    private static double PopulationGraph(double max, double k, double A, double t)
-    {
-        return max / (1 + A * Math.Exp(-k * t));
-    }
 }