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  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4. using System.Drawing;
  5.  
  6. public class Program
  7. {
  8.     /// <summary>
  9.     /// Gets the value at a given X using the line of best fit (Least Square Method) to determine the equation
  10.     /// </summary>
  11.     /// <param name="points">Points to calculate the value from</param>
  12.     /// <param name="x">Function input</param>
  13.     /// <returns>Value at X in the given points</returns>
  14.     public static float LeastSquaresValueAtX(List<PointF> points, float x)
  15.     {
  16.         float slope = SlopeOfPoints(points);
  17.         float yIntercept = YInterceptOfPoints(points, slope);
  18.  
  19.         return (slope * x) + yIntercept;
  20.     }
  21.  
  22.     /// <summary>
  23.     /// Gets the slope for a set of points using the formula:
  24.     /// m = ? (x-AVG(x)(y-AVG(y)) / ? (x-AVG(x))²
  25.     /// </summary>
  26.     /// <param name="points">Points to calculate the Slope from</param>
  27.     /// <returns>SlopeOfPoints</returns>
  28.     private static float SlopeOfPoints(List<PointF> points)
  29.     {
  30.         float xBar = points.Average(p => p.X);
  31.         float yBar = points.Average(p => p.Y);
  32.  
  33.         float dividend = points.Sum(p => (p.X - xBar) * (p.Y - yBar));
  34.         float divisor = (float)points.Sum(p => Math.Pow(p.X - xBar, 2));
  35.  
  36.         return dividend / divisor;            
  37.     }
  38.  
  39.     /// <summary>
  40.     /// Gets the Y-Intercept for a set of points using the formula:
  41.     /// b = AVG(y) - m( AVG(x) )
  42.     /// </summary>
  43.     /// <param name="points">Points to calculate the intercept from</param>
  44.     /// <returns>Y-Intercept</returns>
  45.     private static float YInterceptOfPoints(List<PointF> points, float slope)
  46.     { 
  47.         float xBar = points.Average(p => p.X);
  48.         float yBar = points.Average(p => p.Y);
  49.  
  50.         return yBar - (slope * xBar);        
  51.     }         
  52.   public static void Main()
  53.   {
  54.     Console.WriteLine("Hello C#");
  55.   }
  56. }
  57.  
Success #stdin #stdout 0s 29672KB
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Hello C#
https://ideone.com/HxZorL
C# > Trend()
language:
C# (gmcs 5.20.1)
created:
9 years ago
visibility:
public

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