Weighted Sum

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WeightedSum
{
    class Program
    {
        static void Main(string[] args)
        {
            string critRangeMinPrompt = "Critical Chance Min: ";
            string critRangeMaxPrompt = "Critical Chance Max: ";
            string tolerancePrompt = "Accurate to how many digits? ";
            string inputError = "Input is not valid.";

            // Common math syntax used; interval is [a, b] where a = min and b = max.
            double a = GetInputForm(critRangeMinPrompt, inputError, 0, 0, 1);
            ClearLine(0, 0);
            Console.Write("Interval: [" + a + ", ]");
            double b = GetInputForm(critRangeMaxPrompt, inputError, 0, 2, 1);
            ClearLine(0, 0);
            Console.Write("Interval: [" + a + ", " + b + "]");

            // If interval is invalid, switch.
            if (a > b)
            {
                double c = b;
                b = a;
                a = c;
            }

            // Tolerance level.
            double tol = Math.Pow(0.1, (int)GetInputForm(tolerancePrompt, inputError, 0, 2));

            // Actually do the math!
            double result = FindPercent(a, b, tol);
            Console.WriteLine("\n" + result*100 + "%");
            Console.ReadLine();
        }

        static double FindCritChance(int x, double xIntercept, double yIntercept, double slope)
        {
            // Piecewise function.
            return slope * 0.05 * (x - 10*xIntercept) - slope * 0.05 * (Math.Abs(x - 10*xIntercept)) + yIntercept;
        }

        static double FindPercent(double min, double max, double tol)
        {
            // This method is a weighted average of a summed piecewise function.
            // Returns the weighted average.

            double sumFactor = FindCritChance(0, (max - min), max, 1);
            double nthWeight = (1 - min);
            double sumWeight = 1;

            for (int n = 1; nthWeight * FindCritChance(n, (max - min), max, 1) > tol; n++)
            {
                sumFactor = sumFactor + nthWeight * FindCritChance(n, (max - min), max, 1);
                sumWeight = sumWeight + nthWeight;
                nthWeight = nthWeight * (1 - FindCritChance(n, (max - min), max, 1));
            }
            return sumFactor/sumWeight;
        }

        static void ClearLine(int lcol, int urow)
        {
            // lcol = left column
            // urow = up row
            // Think of the console window as a group of cells.  Cell (0,0) is at the top left of the screen.

            Console.SetCursorPosition(lcol, urow);
            Console.Write(new string(' ', Console.WindowWidth - lcol));
            Console.SetCursorPosition(lcol, urow);
        } // Necessary for GetInputForm.

        static double GetInputForm(string prompt, string error, int lcol, int urow)
        {
            // Asks user for numerical input.
            // Only accepts valid input.

            ClearLine(lcol, urow);
            Console.Write(prompt);
            string inputString = Console.ReadLine();
            double outputDouble;
            while (inputString == null || double.TryParse(inputString, out outputDouble) == false)
            {
                Console.SetCursorPosition(lcol, urow + 2);
                Console.Write(error);
                Console.SetCursorPosition(lcol, urow);
                Console.Write(prompt);
                ClearLine(prompt.Length, urow);
                inputString = Console.ReadLine();
            }
            ClearLine(0, urow + 2);
            return outputDouble;
        }

        static double GetInputForm(string prompt, string error, int lcol, int urow, double maxValue)
        {
            // Overloaded method for GetInputForm.
            // Only accepts input less than or equal to maxValue.

            ClearLine(lcol, urow);
            Console.Write(prompt);
            string inputString = Console.ReadLine();
            double outputDouble;
            while (inputString == null || double.TryParse(inputString, out outputDouble) == false || outputDouble > maxValue)
            {
                Console.SetCursorPosition(lcol, urow + 2);
                Console.Write(error);
                Console.SetCursorPosition(lcol, urow);
                Console.Write(prompt);
                ClearLine(prompt.Length, urow);
                inputString = Console.ReadLine();
            }
            ClearLine(0, urow + 2);
            return outputDouble;
        }
    }

}